diff --git a/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java b/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java
index 9d2bc141c6..d075741490 100644
--- a/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java
+++ b/spring-aop/src/main/java/org/springframework/aop/aspectj/TypePatternClassFilter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@ import org.springframework.util.StringUtils;
  * Spring AOP {@link ClassFilter} implementation using AspectJ type matching.
  *
  * @author Rod Johnson
+ * @author Juergen Hoeller
  * @since 2.0
  */
 public class TypePatternClassFilter implements ClassFilter {
@@ -76,17 +77,21 @@ public class TypePatternClassFilter implements ClassFilter {
 	 * or is recognized as invalid
 	 */
 	public void setTypePattern(String typePattern) {
-		Assert.notNull(typePattern);
+		Assert.notNull(typePattern, "Type pattern must not be null");
 		this.typePattern = typePattern;
 		this.aspectJTypePatternMatcher =
 				PointcutParser.getPointcutParserSupportingAllPrimitivesAndUsingContextClassloaderForResolution().
 				parseTypePattern(replaceBooleanOperators(typePattern));
 	}
 
+	/**
+	 * Return the AspectJ type pattern to match.
+	 */
 	public String getTypePattern() {
-		return typePattern;
+		return this.typePattern;
 	}
 
+
 	/**
 	 * Should the pointcut apply to the given interface or target class?
 	 * @param clazz candidate target class
@@ -95,9 +100,7 @@ public class TypePatternClassFilter implements ClassFilter {
 	 */
 	@Override
 	public boolean matches(Class<?> clazz) {
-		if (this.aspectJTypePatternMatcher == null) {
-			throw new IllegalStateException("No 'typePattern' has been set via ctor/setter.");
-		}
+		Assert.state(this.aspectJTypePatternMatcher != null, "No type pattern has been set");
 		return this.aspectJTypePatternMatcher.matches(clazz);
 	}
 
@@ -108,9 +111,8 @@ public class TypePatternClassFilter implements ClassFilter {
 	 * <p>This method converts back to {@code &&} for the AspectJ pointcut parser.
 	 */
 	private String replaceBooleanOperators(String pcExpr) {
-		pcExpr = StringUtils.replace(pcExpr," and "," && ");
-		pcExpr = StringUtils.replace(pcExpr, " or ", " || ");
-		pcExpr = StringUtils.replace(pcExpr, " not ", " ! ");
-		return pcExpr;
+		String result = StringUtils.replace(pcExpr," and "," && ");
+		result = StringUtils.replace(result, " or ", " || ");
+		return StringUtils.replace(result, " not ", " ! ");
 	}
 }
diff --git a/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java b/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java
index 92fc174bea..d7a8d1168b 100644
--- a/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java
+++ b/spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -54,7 +54,8 @@ public abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyC
 	public void setBeanFactory(BeanFactory beanFactory) {
 		super.setBeanFactory(beanFactory);
 		if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
-			throw new IllegalStateException("Cannot use AdvisorAutoProxyCreator without a ConfigurableListableBeanFactory");
+			throw new IllegalArgumentException(
+					"AdvisorAutoProxyCreator requires a ConfigurableListableBeanFactory: " + beanFactory);
 		}
 		initBeanFactory((ConfigurableListableBeanFactory) beanFactory);
 	}
diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java
index f95c57cd70..ac80c0e059 100644
--- a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java
+++ b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -223,7 +223,7 @@ public class AutowiredAnnotationBeanPostProcessor extends InstantiationAwareBean
 	public void setBeanFactory(BeanFactory beanFactory) {
 		if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
 			throw new IllegalArgumentException(
-					"AutowiredAnnotationBeanPostProcessor requires a ConfigurableListableBeanFactory");
+					"AutowiredAnnotationBeanPostProcessor requires a ConfigurableListableBeanFactory: " + beanFactory);
 		}
 		this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
 	}
diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java b/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java
index dc1516ab02..a110bc4461 100644
--- a/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java
+++ b/spring-beans/src/main/java/org/springframework/beans/factory/config/CustomScopeConfigurer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -102,12 +102,12 @@ public class CustomScopeConfigurer implements BeanFactoryPostProcessor, BeanClas
 				}
 				else if (value instanceof Class) {
 					Class<?> scopeClass = (Class<?>) value;
-					Assert.isAssignable(Scope.class, scopeClass);
+					Assert.isAssignable(Scope.class, scopeClass, "Invalid scope class");
 					beanFactory.registerScope(scopeKey, (Scope) BeanUtils.instantiateClass(scopeClass));
 				}
 				else if (value instanceof String) {
 					Class<?> scopeClass = ClassUtils.resolveClassName((String) value, this.beanClassLoader);
-					Assert.isAssignable(Scope.class, scopeClass);
+					Assert.isAssignable(Scope.class, scopeClass, "Invalid scope class");
 					beanFactory.registerScope(scopeKey, (Scope) BeanUtils.instantiateClass(scopeClass));
 				}
 				else {
diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java b/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java
index ab1a92dd68..324deb7ac5 100644
--- a/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java
+++ b/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -766,7 +766,7 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 	@Override
 	public void registerCustomEditor(Class<?> requiredType, Class<? extends PropertyEditor> propertyEditorClass) {
 		Assert.notNull(requiredType, "Required type must not be null");
-		Assert.isAssignable(PropertyEditor.class, propertyEditorClass);
+		Assert.notNull(propertyEditorClass, "PropertyEditor class must not be null");
 		this.customEditors.put(requiredType, propertyEditorClass);
 	}
 
diff --git a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java
index 64d4d2c2ee..a54429203b 100644
--- a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java
+++ b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultCacheInvocationContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,14 +44,15 @@ class DefaultCacheInvocationContext<A extends Annotation>
 
 	private final CacheInvocationParameter[] allParameters;
 
-	public DefaultCacheInvocationContext(JCacheOperation<A> operation,
-			Object target, Object[] args) {
+
+	public DefaultCacheInvocationContext(JCacheOperation<A> operation, Object target, Object[] args) {
 		this.operation = operation;
 		this.target = target;
 		this.args = args;
 		this.allParameters = operation.getAllParameters(args);
 	}
 
+
 	@Override
 	public JCacheOperation<A> getOperation() {
 		return this.operation;
@@ -94,17 +95,19 @@ class DefaultCacheInvocationContext<A extends Annotation>
 
 	@Override
 	public <T> T unwrap(Class<T> cls) {
-		throw new IllegalArgumentException("Could not unwrap to '" + cls.getName() + "'");
+		throw new IllegalArgumentException("Cannot unwrap to " + cls);
 	}
 
+
 	@Override
 	public String toString() {
-		final StringBuilder sb = new StringBuilder("CacheInvocationContext{");
-		sb.append("operation=").append(operation);
-		sb.append(", target=").append(target);
-		sb.append(", args=").append(Arrays.toString(args));
-		sb.append(", allParameters=").append(Arrays.toString(allParameters));
+		StringBuilder sb = new StringBuilder("CacheInvocationContext{");
+		sb.append("operation=").append(this.operation);
+		sb.append(", target=").append(this.target);
+		sb.append(", args=").append(Arrays.toString(this.args));
+		sb.append(", allParameters=").append(Arrays.toString(this.allParameters));
 		sb.append('}');
 		return sb.toString();
 	}
+
 }
diff --git a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java
index b20f7bbe25..8e960c85e1 100644
--- a/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java
+++ b/spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/JCacheAspectSupport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -66,7 +66,7 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial
 
 
 	public void setCacheOperationSource(JCacheOperationSource cacheOperationSource) {
-		Assert.notNull(cacheOperationSource);
+		Assert.notNull(cacheOperationSource, "JCacheOperationSource must not be null");
 		this.cacheOperationSource = cacheOperationSource;
 	}
 
@@ -80,7 +80,7 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial
 	public void afterPropertiesSet() {
 		Assert.state(getCacheOperationSource() != null, "The 'cacheOperationSource' property is required: " +
 				"If there are no cacheable methods, then don't use a cache aspect.");
-		Assert.state(getErrorHandler() != null, "The 'errorHandler' is required");
+		Assert.state(getErrorHandler() != null, "The 'errorHandler' property is required");
 
 		this.cacheResultInterceptor = new CacheResultInterceptor(getErrorHandler());
 		this.cachePutInterceptor = new CachePutInterceptor(getErrorHandler());
@@ -128,23 +128,23 @@ public class JCacheAspectSupport extends AbstractCacheInvoker implements Initial
 		BasicOperation operation = context.getOperation();
 
 		if (operation instanceof CacheResultOperation) {
-			return cacheResultInterceptor.invoke(
+			return this.cacheResultInterceptor.invoke(
 					(CacheOperationInvocationContext<CacheResultOperation>) context, adapter);
 		}
 		else if (operation instanceof CachePutOperation) {
-			return cachePutInterceptor.invoke(
+			return this.cachePutInterceptor.invoke(
 					(CacheOperationInvocationContext<CachePutOperation>) context, adapter);
 		}
 		else if (operation instanceof CacheRemoveOperation) {
-			return cacheRemoveEntryInterceptor.invoke(
+			return this.cacheRemoveEntryInterceptor.invoke(
 					(CacheOperationInvocationContext<CacheRemoveOperation>) context, adapter);
 		}
 		else if (operation instanceof CacheRemoveAllOperation) {
-			return cacheRemoveAllInterceptor.invoke(
+			return this.cacheRemoveAllInterceptor.invoke(
 					(CacheOperationInvocationContext<CacheRemoveAllOperation>) context, adapter);
 		}
 		else {
-			throw new IllegalArgumentException("Could not handle " + operation);
+			throw new IllegalArgumentException("Cannot handle " + operation);
 		}
 	}
 
diff --git a/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java b/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java
index 8d93e9884a..f53736e521 100644
--- a/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java
+++ b/spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,6 @@ import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.support.PropertiesLoaderUtils;
 import org.springframework.scheduling.SchedulingException;
-import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -210,7 +209,6 @@ public class SchedulerFactoryBean extends SchedulerAccessor implements FactoryBe
 	 * @see #setQuartzProperties
 	 */
 	public void setSchedulerFactoryClass(Class<? extends SchedulerFactory> schedulerFactoryClass) {
-		Assert.isAssignable(SchedulerFactory.class, schedulerFactoryClass);
 		this.schedulerFactoryClass = schedulerFactoryClass;
 	}
 
diff --git a/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java b/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java
index b15c215f7e..56fc64be85 100644
--- a/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java
+++ b/spring-context-support/src/test/java/org/springframework/cache/jcache/interceptor/CacheResolverAdapterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,8 +30,6 @@ import org.junit.rules.ExpectedException;
 
 import org.springframework.cache.Cache;
 import org.springframework.cache.jcache.AbstractJCacheTests;
-import org.springframework.util.Assert;
-import org.springframework.util.ReflectionUtils;
 
 import static org.junit.Assert.*;
 import static org.mockito.BDDMockito.*;
@@ -46,7 +44,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests {
 
 
 	@Test
-	public void resolveSimpleCache() {
+	public void resolveSimpleCache() throws Exception {
 		DefaultCacheInvocationContext<?> dummyContext = createDummyContext();
 		CacheResolverAdapter adapter = new CacheResolverAdapter(getCacheResolver(dummyContext, "testCache"));
 		Collection<? extends Cache> caches = adapter.resolveCaches(dummyContext);
@@ -56,7 +54,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests {
 	}
 
 	@Test
-	public void resolveUnknownCache() {
+	public void resolveUnknownCache() throws Exception {
 		DefaultCacheInvocationContext<?> dummyContext = createDummyContext();
 		CacheResolverAdapter adapter = new CacheResolverAdapter(getCacheResolver(dummyContext, null));
 
@@ -66,7 +64,7 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests {
 
 	protected CacheResolver getCacheResolver(CacheInvocationContext<? extends Annotation> context, String cacheName) {
 		CacheResolver cacheResolver = mock(CacheResolver.class);
-		final javax.cache.Cache cache;
+		javax.cache.Cache cache;
 		if (cacheName == null) {
 			cache = null;
 		}
@@ -78,22 +76,21 @@ public class CacheResolverAdapterTests extends AbstractJCacheTests {
 		return cacheResolver;
 	}
 
-	protected DefaultCacheInvocationContext<?> createDummyContext() {
-		Method method = ReflectionUtils.findMethod(Sample.class, "get", String.class);
-		Assert.notNull(method);
+	protected DefaultCacheInvocationContext<?> createDummyContext() throws Exception {
+		Method method = Sample.class.getMethod("get", String.class);
 		CacheResult cacheAnnotation = method.getAnnotation(CacheResult.class);
 		CacheMethodDetails<CacheResult> methodDetails =
 				new DefaultCacheMethodDetails<>(method, cacheAnnotation, "test");
 		CacheResultOperation operation = new CacheResultOperation(methodDetails,
 				defaultCacheResolver, defaultKeyGenerator, defaultExceptionCacheResolver);
-		return new DefaultCacheInvocationContext<CacheResult>(operation, new Sample(), new Object[] {"id"});
+		return new DefaultCacheInvocationContext<>(operation, new Sample(), new Object[] {"id"});
 	}
 
 
 	static class Sample {
 
 		@CacheResult
-		private Object get(String id) {
+		public Object get(String id) {
 			return null;
 		}
 	}
diff --git a/spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java b/spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java
index 4d3da40022..81edc06703 100644
--- a/spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java
+++ b/spring-context/src/main/java/org/springframework/cache/interceptor/AbstractCacheInvoker.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,7 +37,7 @@ public abstract class AbstractCacheInvoker {
 	}
 
 	protected AbstractCacheInvoker(CacheErrorHandler errorHandler) {
-		Assert.notNull("ErrorHandler must not be null");
+		Assert.notNull(errorHandler, "ErrorHandler must not be null");
 		this.errorHandler = errorHandler;
 	}
 
diff --git a/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java b/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java
index 271b59f1e6..952f6c7d68 100644
--- a/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java
+++ b/spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperation.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -145,19 +145,19 @@ public abstract class CacheOperation implements BasicOperation {
 		private String condition = "";
 
 		public void setName(String name) {
-			Assert.hasText(name);
+			Assert.hasText(name, "Name must not be empty");
 			this.name = name;
 		}
 
 		public void setCacheName(String cacheName) {
-			Assert.hasText(cacheName);
+			Assert.hasText(cacheName, "Cache name must not be empty");
 			this.cacheNames = Collections.singleton(cacheName);
 		}
 
 		public void setCacheNames(String... cacheNames) {
 			this.cacheNames = new LinkedHashSet<String>(cacheNames.length);
 			for (String cacheName : cacheNames) {
-				Assert.hasText(cacheName, "Cache name must be non-null if specified");
+				Assert.hasText(cacheName, "Cache name must be non-empty if specified");
 				this.cacheNames.add(cacheName);
 			}
 		}
@@ -167,7 +167,7 @@ public abstract class CacheOperation implements BasicOperation {
 		}
 
 		public void setKey(String key) {
-			Assert.notNull(key);
+			Assert.notNull(key, "Key must not be null");
 			this.key = key;
 		}
 
@@ -188,22 +188,22 @@ public abstract class CacheOperation implements BasicOperation {
 		}
 
 		public void setKeyGenerator(String keyGenerator) {
-			Assert.notNull(keyGenerator);
+			Assert.notNull(keyGenerator, "KeyGenerator name must not be null");
 			this.keyGenerator = keyGenerator;
 		}
 
 		public void setCacheManager(String cacheManager) {
-			Assert.notNull(cacheManager);
+			Assert.notNull(cacheManager, "CacheManager name must not be null");
 			this.cacheManager = cacheManager;
 		}
 
 		public void setCacheResolver(String cacheResolver) {
-			Assert.notNull(this.cacheManager);
+			Assert.notNull(cacheResolver, "CacheResolver name must not be null");
 			this.cacheResolver = cacheResolver;
 		}
 
 		public void setCondition(String condition) {
-			Assert.notNull(condition);
+			Assert.notNull(condition, "Condition must not be null");
 			this.condition = condition;
 		}
 
diff --git a/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java b/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java
index 2e7047389f..1fbbd23bfc 100644
--- a/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java
+++ b/spring-context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -143,7 +143,7 @@ class ComponentScanAnnotationParser {
 			switch (filterType) {
 				case ANNOTATION:
 					Assert.isAssignable(Annotation.class, filterClass,
-							"An error occurred while processing a @ComponentScan ANNOTATION type filter: ");
+							"@ComponentScan ANNOTATION type filter requires an annotation type");
 					@SuppressWarnings("unchecked")
 					Class<Annotation> annotationType = (Class<Annotation>) filterClass;
 					typeFilters.add(new AnnotationTypeFilter(annotationType));
@@ -153,7 +153,7 @@ class ComponentScanAnnotationParser {
 					break;
 				case CUSTOM:
 					Assert.isAssignable(TypeFilter.class, filterClass,
-							"An error occurred while processing a @ComponentScan CUSTOM type filter: ");
+							"@ComponentScan CUSTOM type filter requires a TypeFilter implementation");
 					TypeFilter filter = BeanUtils.instantiateClass(filterClass, TypeFilter.class);
 					ParserStrategyUtils.invokeAwareMethods(
 							filter, this.environment, this.resourceLoader, this.registry);
diff --git a/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java b/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java
index ec8e6916f0..81268227d7 100644
--- a/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java
+++ b/spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,7 +39,6 @@ import org.springframework.context.Lifecycle;
 import org.springframework.context.LifecycleProcessor;
 import org.springframework.context.Phased;
 import org.springframework.context.SmartLifecycle;
-import org.springframework.util.Assert;
 
 /**
  * Default implementation of the {@link LifecycleProcessor} strategy.
@@ -70,7 +69,10 @@ public class DefaultLifecycleProcessor implements LifecycleProcessor, BeanFactor
 
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) {
-		Assert.isInstanceOf(ConfigurableListableBeanFactory.class, beanFactory);
+		if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
+			throw new IllegalArgumentException(
+					"DefaultLifecycleProcessor requires a ConfigurableListableBeanFactory: " + beanFactory);
+		}
 		this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
 	}
 
diff --git a/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java b/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java
index fb4f50b383..edddb0d552 100644
--- a/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java
+++ b/spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -128,7 +128,7 @@ public class DateTimeFormatterFactory {
 	 * @param style two characters from the set {"S", "M", "L", "F", "-"}
 	 */
 	public void setStylePattern(String style) {
-		Assert.isTrue(style != null && style.length() == 2);
+		Assert.isTrue(style != null && style.length() == 2, "Style pattern must consist of two characters");
 		this.dateStyle = convertStyleCharacter(style.charAt(0));
 		this.timeStyle = convertStyleCharacter(style.charAt(1));
 	}
diff --git a/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java b/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java
index 2f74120590..7a2a74afda 100644
--- a/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java
+++ b/spring-context/src/main/java/org/springframework/instrument/classloading/weblogic/WebLogicClassLoaderAdapter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,7 +55,7 @@ class WebLogicClassLoaderAdapter {
 
 
 	public WebLogicClassLoaderAdapter(ClassLoader classLoader) {
-		Class<?> wlGenericClassLoaderClass = null;
+		Class<?> wlGenericClassLoaderClass;
 		try {
 			wlGenericClassLoaderClass = classLoader.loadClass(GENERIC_CLASS_LOADER_NAME);
 			this.wlPreProcessorClass = classLoader.loadClass(CLASS_PRE_PROCESSOR_NAME);
@@ -66,12 +66,14 @@ class WebLogicClassLoaderAdapter {
 			this.wlGenericClassLoaderConstructor = wlGenericClassLoaderClass.getConstructor(
 					this.getClassFinderMethod.getReturnType(), ClassLoader.class);
 		}
-		catch (Exception ex) {
+		catch (Throwable ex) {
 			throw new IllegalStateException(
 					"Could not initialize WebLogic LoadTimeWeaver because WebLogic 10 API classes are not available", ex);
 		}
-		Assert.isInstanceOf(wlGenericClassLoaderClass, classLoader,
-				"ClassLoader must be instance of [" + wlGenericClassLoaderClass.getName() + "]");
+		if (!wlGenericClassLoaderClass.isInstance(classLoader)) {
+			throw new IllegalArgumentException(
+					"ClassLoader must be an instance of [" + wlGenericClassLoaderClass.getName() + "]: " + classLoader);
+		}
 		this.classLoader = classLoader;
 	}
 
@@ -87,7 +89,7 @@ class WebLogicClassLoaderAdapter {
 		catch (InvocationTargetException ex) {
 			throw new IllegalStateException("WebLogic addInstanceClassPreProcessor method threw exception", ex.getCause());
 		}
-		catch (Exception ex) {
+		catch (Throwable ex) {
 			throw new IllegalStateException("Could not invoke WebLogic addInstanceClassPreProcessor method", ex);
 		}
 	}
@@ -106,8 +108,9 @@ class WebLogicClassLoaderAdapter {
 		catch (InvocationTargetException ex) {
 			throw new IllegalStateException("WebLogic GenericClassLoader constructor failed", ex.getCause());
 		}
-		catch (Exception ex) {
+		catch (Throwable ex) {
 			throw new IllegalStateException("Could not construct WebLogic GenericClassLoader", ex);
 		}
 	}
+
 }
diff --git a/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java b/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java
index 19bb244bff..2d17df795b 100644
--- a/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java
+++ b/spring-context/src/test/java/org/springframework/aop/framework/ClassWithComplexConstructor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,7 +33,7 @@ public class ClassWithComplexConstructor {
 
 	@Autowired
 	public ClassWithComplexConstructor(Dependency dependency) {
-		Assert.notNull(dependency);
+		Assert.notNull(dependency, "No Dependency bean injected");
 		this.dependency = dependency;
 	}
 
@@ -42,7 +42,8 @@ public class ClassWithComplexConstructor {
 	}
 
 	public void method() {
-		Assert.isTrue(this.selfReference != this && AopUtils.isCglibProxy(this.selfReference));
+		Assert.state(this.selfReference != this && AopUtils.isCglibProxy(this.selfReference),
+				"Self reference must be a CGLIB proxy");
 		this.dependency.method();
 	}
 
diff --git a/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java b/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java
index 25da88cf3f..a8eec500df 100644
--- a/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java
+++ b/spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1250,7 +1250,7 @@ public class ConfigurationClassPostProcessorTests {
 
 		@PostConstruct
 		public void validate() {
-			Assert.notNull(provider);
+			Assert.notNull(provider, "No ServiceBeanProvider injected");
 		}
 	}
 
@@ -1291,7 +1291,7 @@ public class ConfigurationClassPostProcessorTests {
 
 		@PostConstruct
 		public void validate() {
-			Assert.notNull(provider);
+			Assert.notNull(provider, "No ServiceBeanProvider injected");
 		}
 	}
 
@@ -1403,7 +1403,7 @@ public class ConfigurationClassPostProcessorTests {
 	static class DependingFoo {
 
 		DependingFoo(BarArgument bar) {
-			Assert.notNull(bar);
+			Assert.notNull(bar, "No BarArgument injected");
 		}
 	}
 
diff --git a/spring-context/src/test/java/org/springframework/context/support/Service.java b/spring-context/src/test/java/org/springframework/context/support/Service.java
index ee9d5095d7..dd9fcd3182 100644
--- a/spring-context/src/test/java/org/springframework/context/support/Service.java
+++ b/spring-context/src/test/java/org/springframework/context/support/Service.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,7 +72,8 @@ public class Service implements ApplicationContextAware, MessageSourceAware, Dis
 		Thread thread = new Thread() {
 			@Override
 			public void run() {
-				Assert.isTrue(applicationContext.getBean("messageSource") instanceof StaticMessageSource);
+				Assert.state(applicationContext.getBean("messageSource") instanceof StaticMessageSource,
+						"Invalid MessageSource bean");
 				try {
 					applicationContext.getBean("service2");
 					// Should have thrown BeanCreationNotAllowedException
diff --git a/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java b/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java
index 2eda9eddd8..75e6515a69 100644
--- a/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java
+++ b/spring-context/src/test/java/org/springframework/format/datetime/standard/DateTimeFormattingTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -355,6 +355,7 @@ public class DateTimeFormattingTests {
 	}
 
 	@Test
+	@SuppressWarnings("deprecation")
 	public void testBindInstantFromJavaUtilDate() throws Exception {
 		MutablePropertyValues propertyValues = new MutablePropertyValues();
 		propertyValues.add("instant", new Date(109, 9, 31, 12, 0));
diff --git a/spring-core/src/main/java/org/springframework/core/Constants.java b/spring-core/src/main/java/org/springframework/core/Constants.java
index 3f8d9737bc..4310b9a478 100644
--- a/spring-core/src/main/java/org/springframework/core/Constants.java
+++ b/spring-core/src/main/java/org/springframework/core/Constants.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -59,7 +59,7 @@ public class Constants {
 	 * @throws IllegalArgumentException if the supplied {@code clazz} is {@code null}
 	 */
 	public Constants(Class<?> clazz) {
-		Assert.notNull(clazz);
+		Assert.notNull(clazz, "Class must not be null");
 		this.className = clazz.getName();
 		Field[] fields = clazz.getFields();
 		for (Field field : fields) {
diff --git a/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java b/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java
index f3d516702f..dcb9c29591 100644
--- a/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java
+++ b/spring-core/src/main/java/org/springframework/core/ParameterizedTypeReference.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,9 +47,9 @@ public abstract class ParameterizedTypeReference<T> {
 	protected ParameterizedTypeReference() {
 		Class<?> parameterizedTypeReferenceSubclass = findParameterizedTypeReferenceSubclass(getClass());
 		Type type = parameterizedTypeReferenceSubclass.getGenericSuperclass();
-		Assert.isInstanceOf(ParameterizedType.class, type);
+		Assert.isInstanceOf(ParameterizedType.class, type, "Type must be a parameterized type");
 		ParameterizedType parameterizedType = (ParameterizedType) type;
-		Assert.isTrue(parameterizedType.getActualTypeArguments().length == 1);
+		Assert.isTrue(parameterizedType.getActualTypeArguments().length == 1, "Number of type arguments must be 1");
 		this.type = parameterizedType.getActualTypeArguments()[0];
 	}
 
diff --git a/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java b/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java
index eaae658a4d..5ed4db0fa2 100644
--- a/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java
+++ b/spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -408,7 +408,10 @@ abstract class SerializableTypeWrapper {
 		private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
 			inputStream.defaultReadObject();
 			this.method = ReflectionUtils.findMethod(this.declaringClass, this.methodName);
-			Assert.state(Type.class == this.method.getReturnType() || Type[].class == this.method.getReturnType());
+			if (this.method.getReturnType() != Type.class && this.method.getReturnType() != Type[].class) {
+				throw new IllegalStateException(
+						"Invalid return type on deserialized method - needs to be Type or Type[]: " + this.method);
+			}
 		}
 	}
 
diff --git a/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java b/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java
index b34e4b9dc4..a2ebe34719 100644
--- a/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java
+++ b/spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,15 +23,15 @@ import java.util.List;
 import joptsimple.OptionSet;
 import joptsimple.OptionSpec;
 
-import org.springframework.util.Assert;
-
 /**
  * {@link CommandLinePropertySource} implementation backed by a JOpt {@link OptionSet}.
  *
  * <h2>Typical usage</h2>
+ *
  * Configure and execute an {@code OptionParser} against the {@code String[]} of arguments
  * supplied to the {@code main} method, and create a {@link JOptCommandLinePropertySource}
  * using the resulting {@code OptionSet} object:
+ *
  * <pre class="code">
  * public static void main(String[] args) {
  *     OptionParser parser = new OptionParser();
@@ -44,7 +44,7 @@ import org.springframework.util.Assert;
  *
  * See {@link CommandLinePropertySource} for complete general usage examples.
  *
- * <p>Requires JOpt version 4.3 or higher. Tested against JOpt up until 4.6.
+ * <p>Requires JOpt Simple version 4.3 or higher. Tested against JOpt up until 5.0.
  *
  * @author Chris Beams
  * @author Juergen Hoeller
@@ -98,7 +98,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource<Opt
 		List<?> argValues = this.source.valuesOf(name);
 		List<String> stringArgValues = new ArrayList<String>();
 		for (Object argValue : argValues) {
-			stringArgValues.add(argValue instanceof String ? (String) argValue : argValue.toString());
+			stringArgValues.add(argValue.toString());
 		}
 		if (stringArgValues.isEmpty()) {
 			return (this.source.has(name) ? Collections.<String>emptyList() : null);
@@ -111,8 +111,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource<Opt
 		List<?> argValues = this.source.nonOptionArguments();
 		List<String> stringArgValues = new ArrayList<String>();
 		for (Object argValue : argValues) {
-			Assert.isInstanceOf(String.class, argValue, "Argument values must be of type String");
-			stringArgValues.add((String) argValue);
+			stringArgValues.add(argValue.toString());
 		}
 		return (stringArgValues.isEmpty() ? Collections.<String>emptyList() :
 				Collections.unmodifiableList(stringArgValues));
diff --git a/spring-core/src/main/java/org/springframework/util/Assert.java b/spring-core/src/main/java/org/springframework/util/Assert.java
index 76b45186be..fa18e522ca 100644
--- a/spring-core/src/main/java/org/springframework/util/Assert.java
+++ b/spring-core/src/main/java/org/springframework/util/Assert.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,20 +48,20 @@ import java.util.Map;
  *
  * @author Keith Donald
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @author Colin Sampaleanu
  * @author Rob Harrop
- * @author Sam Brannen
  * @since 1.1.2
  */
 public abstract class Assert {
 
 	/**
-	 * Assert a boolean expression, throwing {@code IllegalArgumentException}
-	 * if the test result is {@code false}.
+	 * Assert a boolean expression, throwing an {@code IllegalArgumentException}
+	 * if the expression evaluates to {@code false}.
 	 * <pre class="code">Assert.isTrue(i &gt; 0, "The value must be greater than zero");</pre>
 	 * @param expression a boolean expression
 	 * @param message the exception message to use if the assertion fails
-	 * @throws IllegalArgumentException if expression is {@code false}
+	 * @throws IllegalArgumentException if {@code expression} is {@code false}
 	 */
 	public static void isTrue(boolean expression, String message) {
 		if (!expression) {
@@ -70,18 +70,15 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert a boolean expression, throwing {@code IllegalArgumentException}
-	 * if the test result is {@code false}.
-	 * <pre class="code">Assert.isTrue(i &gt; 0);</pre>
-	 * @param expression a boolean expression
-	 * @throws IllegalArgumentException if expression is {@code false}
+	 * @deprecated as of 4.3.7, in favor of {@link #isTrue(boolean, String)}
 	 */
+	@Deprecated
 	public static void isTrue(boolean expression) {
 		isTrue(expression, "[Assertion failed] - this expression must be true");
 	}
 
 	/**
-	 * Assert that an object is {@code null} .
+	 * Assert that an object is {@code null}.
 	 * <pre class="code">Assert.isNull(value, "The value must be null");</pre>
 	 * @param object the object to check
 	 * @param message the exception message to use if the assertion fails
@@ -94,17 +91,15 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that an object is {@code null} .
-	 * <pre class="code">Assert.isNull(value);</pre>
-	 * @param object the object to check
-	 * @throws IllegalArgumentException if the object is not {@code null}
+	 * @deprecated as of 4.3.7, in favor of {@link #isNull(Object, String)}
 	 */
+	@Deprecated
 	public static void isNull(Object object) {
 		isNull(object, "[Assertion failed] - the object argument must be null");
 	}
 
 	/**
-	 * Assert that an object is not {@code null} .
+	 * Assert that an object is not {@code null}.
 	 * <pre class="code">Assert.notNull(clazz, "The class must not be null");</pre>
 	 * @param object the object to check
 	 * @param message the exception message to use if the assertion fails
@@ -117,11 +112,9 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that an object is not {@code null} .
-	 * <pre class="code">Assert.notNull(clazz);</pre>
-	 * @param object the object to check
-	 * @throws IllegalArgumentException if the object is {@code null}
+	 * @deprecated as of 4.3.7, in favor of {@link #notNull(Object, String)}
 	 */
+	@Deprecated
 	public static void notNull(Object object) {
 		notNull(object, "[Assertion failed] - this argument is required; it must not be null");
 	}
@@ -142,20 +135,16 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that the given String is not empty; that is,
-	 * it must not be {@code null} and not the empty String.
-	 * <pre class="code">Assert.hasLength(name);</pre>
-	 * @param text the String to check
-	 * @see StringUtils#hasLength
-	 * @throws IllegalArgumentException if the text is empty
+	 * @deprecated as of 4.3.7, in favor of {@link #hasLength(String, String)}
 	 */
+	@Deprecated
 	public static void hasLength(String text) {
 		hasLength(text,
 				"[Assertion failed] - this String argument must have length; it must not be null or empty");
 	}
 
 	/**
-	 * Assert that the given String has valid text content; that is, it must not
+	 * Assert that the given String contains valid text content; that is, it must not
 	 * be {@code null} and must contain at least one non-whitespace character.
 	 * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
 	 * @param text the String to check
@@ -170,13 +159,9 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that the given String has valid text content; that is, it must not
-	 * be {@code null} and must contain at least one non-whitespace character.
-	 * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
-	 * @param text the String to check
-	 * @see StringUtils#hasText
-	 * @throws IllegalArgumentException if the text does not contain valid text content
+	 * @deprecated as of 4.3.7, in favor of {@link #hasText(String, String)}
 	 */
+	@Deprecated
 	public static void hasText(String text) {
 		hasText(text,
 				"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
@@ -198,24 +183,21 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that the given text does not contain the given substring.
-	 * <pre class="code">Assert.doesNotContain(name, "rod");</pre>
-	 * @param textToSearch the text to search
-	 * @param substring the substring to find within the text
-	 * @throws IllegalArgumentException if the text contains the substring
+	 * @deprecated as of 4.3.7, in favor of {@link #doesNotContain(String, String, String)}
 	 */
+	@Deprecated
 	public static void doesNotContain(String textToSearch, String substring) {
 		doesNotContain(textToSearch, substring,
 				"[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
 	}
 
 	/**
-	 * Assert that an array has elements; that is, it must not be
-	 * {@code null} and must have at least one element.
-	 * <pre class="code">Assert.notEmpty(array, "The array must have elements");</pre>
+	 * Assert that an array contains elements; that is, it must not be
+	 * {@code null} and must contain at least one element.
+	 * <pre class="code">Assert.notEmpty(array, "The array must contain elements");</pre>
 	 * @param array the array to check
 	 * @param message the exception message to use if the assertion fails
-	 * @throws IllegalArgumentException if the object array is {@code null} or has no elements
+	 * @throws IllegalArgumentException if the object array is {@code null} or contains no elements
 	 */
 	public static void notEmpty(Object[] array, String message) {
 		if (ObjectUtils.isEmpty(array)) {
@@ -224,20 +206,17 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that an array has elements; that is, it must not be
-	 * {@code null} and must have at least one element.
-	 * <pre class="code">Assert.notEmpty(array);</pre>
-	 * @param array the array to check
-	 * @throws IllegalArgumentException if the object array is {@code null} or has no elements
+	 * @deprecated as of 4.3.7, in favor of {@link #notEmpty(Object[], String)}
 	 */
+	@Deprecated
 	public static void notEmpty(Object[] array) {
 		notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
 	}
 
 	/**
-	 * Assert that an array has no null elements.
-	 * Note: Does not complain if the array is empty!
-	 * <pre class="code">Assert.noNullElements(array, "The array must have non-null elements");</pre>
+	 * Assert that an array contains no {@code null} elements.
+	 * <p>Note: Does not complain if the array is empty!
+	 * <pre class="code">Assert.noNullElements(array, "The array must contain non-null elements");</pre>
 	 * @param array the array to check
 	 * @param message the exception message to use if the assertion fails
 	 * @throws IllegalArgumentException if the object array contains a {@code null} element
@@ -253,23 +232,21 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that an array has no null elements.
-	 * Note: Does not complain if the array is empty!
-	 * <pre class="code">Assert.noNullElements(array);</pre>
-	 * @param array the array to check
-	 * @throws IllegalArgumentException if the object array contains a {@code null} element
+	 * @deprecated as of 4.3.7, in favor of {@link #noNullElements(Object[], String)}
 	 */
+	@Deprecated
 	public static void noNullElements(Object[] array) {
 		noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
 	}
 
 	/**
-	 * Assert that a collection has elements; that is, it must not be
-	 * {@code null} and must have at least one element.
-	 * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
+	 * Assert that a collection contains elements; that is, it must not be
+	 * {@code null} and must contain at least one element.
+	 * <pre class="code">Assert.notEmpty(collection, "Collection must contain elements");</pre>
 	 * @param collection the collection to check
 	 * @param message the exception message to use if the assertion fails
-	 * @throws IllegalArgumentException if the collection is {@code null} or has no elements
+	 * @throws IllegalArgumentException if the collection is {@code null} or
+	 * contains no elements
 	 */
 	public static void notEmpty(Collection<?> collection, String message) {
 		if (CollectionUtils.isEmpty(collection)) {
@@ -278,24 +255,21 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that a collection has elements; that is, it must not be
-	 * {@code null} and must have at least one element.
-	 * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
-	 * @param collection the collection to check
-	 * @throws IllegalArgumentException if the collection is {@code null} or has no elements
+	 * @deprecated as of 4.3.7, in favor of {@link #notEmpty(Collection, String)}
 	 */
+	@Deprecated
 	public static void notEmpty(Collection<?> collection) {
 		notEmpty(collection,
 				"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
 	}
 
 	/**
-	 * Assert that a Map has entries; that is, it must not be {@code null}
-	 * and must have at least one entry.
-	 * <pre class="code">Assert.notEmpty(map, "Map must have entries");</pre>
+	 * Assert that a Map contains entries; that is, it must not be {@code null}
+	 * and must contain at least one entry.
+	 * <pre class="code">Assert.notEmpty(map, "Map must contain entries");</pre>
 	 * @param map the map to check
 	 * @param message the exception message to use if the assertion fails
-	 * @throws IllegalArgumentException if the map is {@code null} or has no entries
+	 * @throws IllegalArgumentException if the map is {@code null} or contains no entries
 	 */
 	public static void notEmpty(Map<?, ?> map, String message) {
 		if (CollectionUtils.isEmpty(map)) {
@@ -304,26 +278,31 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that a Map has entries; that is, it must not be {@code null}
-	 * and must have at least one entry.
-	 * <pre class="code">Assert.notEmpty(map);</pre>
-	 * @param map the map to check
-	 * @throws IllegalArgumentException if the map is {@code null} or has no entries
+	 * @deprecated as of 4.3.7, in favor of {@link #notEmpty(Map, String)}
 	 */
+	@Deprecated
 	public static void notEmpty(Map<?, ?> map) {
 		notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
 	}
 
 	/**
 	 * Assert that the provided object is an instance of the provided class.
-	 * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
-	 * @param clazz the required class
+	 * <pre class="code">Assert.instanceOf(Foo.class, foo, "Processing Foo:");</pre>
+	 * @param type the type to check against
 	 * @param obj the object to check
-	 * @throws IllegalArgumentException if the object is not an instance of clazz
+	 * @param message a message which will be prepended to the message generated
+	 * by this method in order to provide further context. It should normally end
+	 * in ":" or "." so that the generated message looks OK when appended to it.
+	 * @throws IllegalArgumentException if the object is not an instance of type
 	 * @see Class#isInstance
 	 */
-	public static void isInstanceOf(Class<?> clazz, Object obj) {
-		isInstanceOf(clazz, obj, "");
+	public static void isInstanceOf(Class<?> type, Object obj, String message) {
+		notNull(type, "Type to check against must not be null");
+		if (!type.isInstance(obj)) {
+			String className = (obj != null ? obj.getClass().getName() : "null");
+			throw new IllegalArgumentException(StringUtils.hasLength(message) ? message + ": " + className :
+					"Object of class [" + className + "] must be an instance of " + type);
+		}
 	}
 
 	/**
@@ -331,20 +310,28 @@ public abstract class Assert {
 	 * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
 	 * @param type the type to check against
 	 * @param obj the object to check
-	 * @param message a message which will be prepended to the message produced by
-	 * the function itself, and which may be used to provide context. It should
-	 * normally end in ":" or "." so that the generated message looks OK when
-	 * appended to it.
-	 * @throws IllegalArgumentException if the object is not an instance of clazz
+	 * @throws IllegalArgumentException if the object is not an instance of type
 	 * @see Class#isInstance
 	 */
-	public static void isInstanceOf(Class<?> type, Object obj, String message) {
-		notNull(type, "Type to check against must not be null");
-		if (!type.isInstance(obj)) {
-			throw new IllegalArgumentException(
-					(StringUtils.hasLength(message) ? message + " " : "") +
-					"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
-					"] must be an instance of " + type);
+	public static void isInstanceOf(Class<?> type, Object obj) {
+		isInstanceOf(type, obj, "");
+	}
+
+	/**
+	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
+	 * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
+	 * @param superType the super type to check against
+	 * @param subType the sub type to check
+	 * @param message a message which will be prepended to the message generated
+	 * by this method in order to provide further context. It should normally end
+	 * in ":" or "." so that the generated message looks OK when appended to it.
+	 * @throws IllegalArgumentException if the classes are not assignable
+	 */
+	public static void isAssignable(Class<?> superType, Class<?> subType, String message) {
+		notNull(superType, "Super type to check against must not be null");
+		if (subType == null || !superType.isAssignableFrom(subType)) {
+			throw new IllegalArgumentException(StringUtils.hasLength(message) ? message + ": " + subType :
+					subType + " is not assignable to " + superType);
 		}
 	}
 
@@ -360,32 +347,14 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
-	 * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
-	 * @param superType the super type to check against
-	 * @param subType the sub type to check
-	 * @param message a message which will be prepended to the message produced by
-	 * the function itself, and which may be used to provide context. It should
-	 * normally end in ":" or "." so that the generated message looks OK when
-	 * appended to it.
-	 * @throws IllegalArgumentException if the classes are not assignable
-	 */
-	public static void isAssignable(Class<?> superType, Class<?> subType, String message) {
-		notNull(superType, "Type to check against must not be null");
-		if (subType == null || !superType.isAssignableFrom(subType)) {
-			throw new IllegalArgumentException((StringUtils.hasLength(message) ? message + " " : "") +
-					subType + " is not assignable to " + superType);
-		}
-	}
-
-	/**
-	 * Assert a boolean expression, throwing {@code IllegalStateException}
-	 * if the test result is {@code false}. Call isTrue if you wish to
-	 * throw IllegalArgumentException on an assertion failure.
+	 * Assert a boolean expression, throwing an {@code IllegalStateException}
+	 * if the expression evaluates to {@code false}.
+	 * <p>Call {@link #isTrue} if you wish to throw an {@code IllegalArgumentException}
+	 * on an assertion failure.
 	 * <pre class="code">Assert.state(id == null, "The id property must not already be initialized");</pre>
 	 * @param expression a boolean expression
 	 * @param message the exception message to use if the assertion fails
-	 * @throws IllegalStateException if expression is {@code false}
+	 * @throws IllegalStateException if {@code expression} is {@code false}
 	 */
 	public static void state(boolean expression, String message) {
 		if (!expression) {
@@ -394,14 +363,9 @@ public abstract class Assert {
 	}
 
 	/**
-	 * Assert a boolean expression, throwing {@link IllegalStateException}
-	 * if the test result is {@code false}.
-	 * <p>Call {@link #isTrue(boolean)} if you wish to
-	 * throw {@link IllegalArgumentException} on an assertion failure.
-	 * <pre class="code">Assert.state(id == null);</pre>
-	 * @param expression a boolean expression
-	 * @throws IllegalStateException if the supplied expression is {@code false}
+	 * @deprecated as of 4.3.7, in favor of {@link #state(boolean, String)}
 	 */
+	@Deprecated
 	public static void state(boolean expression) {
 		state(expression, "[Assertion failed] - this state invariant must be true");
 	}
diff --git a/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java b/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
index 7710ed273d..ff2c36717a 100644
--- a/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
+++ b/spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -903,7 +903,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 
 		@Override
 		public void remove() {
-			Assert.state(this.last != null);
+			Assert.state(this.last != null, "No element to remove");
 			ConcurrentReferenceHashMap.this.remove(this.last.getKey());
 		}
 	}
diff --git a/spring-core/src/test/java/org/springframework/util/AssertTests.java b/spring-core/src/test/java/org/springframework/util/AssertTests.java
index b3c5d43335..00ee6ef877 100644
--- a/spring-core/src/test/java/org/springframework/util/AssertTests.java
+++ b/spring-core/src/test/java/org/springframework/util/AssertTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,18 +16,15 @@
 
 package org.springframework.util;
 
-import java.util.ArrayList;
 import java.util.Collection;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
 import java.util.Map;
-import java.util.Set;
 
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
+import static java.util.Collections.*;
+
 /**
  * Unit tests for the {@link Assert} class.
  *
@@ -36,146 +33,249 @@ import org.junit.rules.ExpectedException;
  * @author Rick Evans
  * @author Arjen Poutsma
  * @author Sam Brannen
+ * @author Juergen Hoeller
  */
 public class AssertTests {
 
 	@Rule
-	public ExpectedException thrown = ExpectedException.none();
+	public final ExpectedException thrown = ExpectedException.none();
 
 
 	@Test
-	public void instanceOf() {
-		Assert.isInstanceOf(HashSet.class, new HashSet<Object>());
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void instanceOfWithTypeMismatch() {
-		Assert.isInstanceOf(HashMap.class, new HashSet<Object>());
+	public void isTrueWithMessage() {
+		Assert.isTrue(true, "enigma");
 	}
 
 	@Test
-	public void instanceOfNoMessage() throws Exception {
+	public void isTrueWithFalse() {
 		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("Object of class [java.lang.Object] must be an instance " +
-				"of interface java.util.Set");
-		Assert.isInstanceOf(Set.class, new Object(), null);
+		thrown.expectMessage("enigma");
+		Assert.isTrue(false, "enigma");
 	}
 
 	@Test
-	public void instanceOfMessage() throws Exception {
-		thrown.expect(IllegalArgumentException.class);
-		thrown.expectMessage("Custom message. Object of class [java.lang.Object] must " +
-				"be an instance of interface java.util.Set");
-		Assert.isInstanceOf(Set.class, new Object(), "Custom message.");
-	}
-
-	@Test
-	public void isNullDoesNotThrowExceptionIfArgumentIsNullWithMessage() {
+	public void isNullWithMessage() {
 		Assert.isNull(null, "Bla");
 	}
 
 	@Test
-	public void isNullDoesNotThrowExceptionIfArgumentIsNull() {
-		Assert.isNull(null);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void isNullThrowsExceptionIfArgumentIsNotNull() {
-		Assert.isNull(new Object());
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void isTrueWithFalseExpressionThrowsException() throws Exception {
-		Assert.isTrue(false);
+	public void notNullWithMessage() {
+		Assert.notNull("foo", "enigma");
 	}
 
 	@Test
-	public void isTrueWithTrueExpressionSunnyDay() throws Exception {
-		Assert.isTrue(true);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void testHasLengthWithNullStringThrowsException() throws Exception {
-		Assert.hasLength(null);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void hasLengthWithEmptyStringThrowsException() throws Exception {
-		Assert.hasLength("");
+	public void hasLength() {
+		Assert.hasLength("I Heart ...", "enigma");
 	}
 
 	@Test
-	public void hasLengthWithWhitespaceOnlyStringDoesNotThrowException() throws Exception {
-		Assert.hasLength("\t  ");
+	public void hasLengthWithWhitespaceOnly() {
+		Assert.hasLength("\t  ", "enigma");
 	}
 
 	@Test
-	public void hasLengthSunnyDay() throws Exception {
-		Assert.hasLength("I Heart ...");
+	public void hasLengthWithEmptyString() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.hasLength("", "enigma");
 	}
 
 	@Test
-	public void doesNotContainWithNullSearchStringDoesNotThrowException() throws Exception {
-		Assert.doesNotContain(null, "rod");
+	public void hasLengthWithNull() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.hasLength(null, "enigma");
 	}
 
 	@Test
-	public void doesNotContainWithNullSubstringDoesNotThrowException() throws Exception {
-		Assert.doesNotContain("A cool chick's name is Brod. ", null);
+	public void hasText() {
+		Assert.hasText("foo", "enigma");
 	}
 
 	@Test
-	public void doesNotContainWithEmptySubstringDoesNotThrowException() throws Exception {
-		Assert.doesNotContain("A cool chick's name is Brod. ", "");
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void assertNotEmptyWithNullCollectionThrowsException() throws Exception {
-		Assert.notEmpty((Collection<?>) null);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void assertNotEmptyWithEmptyCollectionThrowsException() throws Exception {
-		Assert.notEmpty(new ArrayList<Object>());
+	public void hasTextWithWhitespaceOnly() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.hasText("\t ", "enigma");
 	}
 
 	@Test
-	public void assertNotEmptyWithCollectionSunnyDay() throws Exception {
-		List<String> collection = new ArrayList<String>();
-		collection.add("");
-		Assert.notEmpty(collection);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void assertNotEmptyWithNullMapThrowsException() throws Exception {
-		Assert.notEmpty((Map<?, ?>) null);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void assertNotEmptyWithEmptyMapThrowsException() throws Exception {
-		Assert.notEmpty(new HashMap<Object, Object>());
+	public void hasTextWithEmptyString() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.hasText("", "enigma");
 	}
 
 	@Test
-	public void assertNotEmptyWithMapSunnyDay() throws Exception {
-		Map<String, String> map = new HashMap<String, String>();
-		map.put("", "");
-		Assert.notEmpty(map);
-	}
-
-	@Test(expected = IllegalArgumentException.class)
-	public void isInstanceofClassWithNullInstanceThrowsException() throws Exception {
-		Assert.isInstanceOf(String.class, null);
-	}
-
-	@Test(expected = IllegalStateException.class)
-	public void stateWithFalseExpressionThrowsException() throws Exception {
-		Assert.state(false);
+	public void hasTextWithNull() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.hasText(null, "enigma");
 	}
 
 	@Test
-	public void stateWithTrueExpressionSunnyDay() throws Exception {
-		Assert.state(true);
+	public void doesNotContainWithNullSearchString() {
+		Assert.doesNotContain(null, "rod", "enigma");
+	}
+
+	@Test
+	public void doesNotContainWithNullSubstring() {
+		Assert.doesNotContain("A cool chick's name is Brod.", null, "enigma");
+	}
+
+	@Test
+	public void doesNotContainWithEmptySubstring() {
+		Assert.doesNotContain("A cool chick's name is Brod.", "", "enigma");
+	}
+
+	@Test
+	public void doesNotContainWithNullSearchStringAndNullSubstring() {
+		Assert.doesNotContain(null, null, "enigma");
+	}
+
+	@Test
+	public void notEmptyArray() {
+		Assert.notEmpty(new String[] {"1234"}, "enigma");
+	}
+
+	@Test
+	public void notEmptyArrayWithEmptyArray() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(new String[] {}, "enigma");
+	}
+
+	@Test
+	public void notEmptyArrayWithNullArray() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Object[]) null, "enigma");
+	}
+
+	@Test
+	public void noNullElements() {
+		Assert.noNullElements(new String[] { "1234" }, "enigma");
+	}
+
+	@Test
+	public void noNullElementsWithEmptyArray() {
+		Assert.noNullElements(new String[] {}, "enigma");
+	}
+
+	@Test
+	public void notEmptyCollection() {
+		Assert.notEmpty(singletonList("foo"), "enigma");
+	}
+
+	@Test
+	public void notEmptyCollectionWithEmptyCollection() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(emptyList(), "enigma");
+	}
+
+	@Test
+	public void notEmptyCollectionWithNullCollection() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Collection<?>) null, "enigma");
+	}
+
+	@Test
+	public void notEmptyMap() {
+		Assert.notEmpty(singletonMap("foo", "bar"), "enigma");
+	}
+
+	@Test
+	public void notEmptyMapWithNullMap() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty((Map<?, ?>) null, "enigma");
+	}
+
+	@Test
+	public void notEmptyMapWithEmptyMap() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma");
+		Assert.notEmpty(emptyMap(), "enigma");
+	}
+
+	@Test
+	public void isInstanceOf() {
+		Assert.isInstanceOf(String.class, "foo", "enigma");
+	}
+
+	@Test
+	public void isInstanceOfWithNullType() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("Type to check against must not be null");
+		Assert.isInstanceOf(null, "foo", "enigma");
+	}
+
+	@Test
+	public void isInstanceOfWithNullInstance() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma: null");
+		Assert.isInstanceOf(String.class, null, "enigma");
+	}
+
+	@Test
+	public void isInstanceOfWithTypeMismatchAndNullMessage() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("Object of class [java.lang.Long] must be an instance of class java.lang.String");
+		Assert.isInstanceOf(String.class, 42L, (String) null);
+	}
+
+	@Test
+	public void isInstanceOfWithTypeMismatchAndCustomMessage() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("Custom message: java.lang.Long");
+		Assert.isInstanceOf(String.class, 42L, "Custom message");
+	}
+
+	@Test
+	public void isAssignable() {
+		Assert.isAssignable(Number.class, Integer.class, "enigma");
+	}
+
+	@Test
+	public void isAssignableWithNullSupertype() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("Super type to check against must not be null");
+		Assert.isAssignable(null, Integer.class, "enigma");
+	}
+
+	@Test
+	public void isAssignableWithNullSubtype() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma: null");
+		Assert.isAssignable(Integer.class, null, "enigma");
+	}
+
+	@Test
+	public void isAssignableWithTypeMismatchAndNullMessage() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("class java.lang.Integer is not assignable to class java.lang.String");
+		Assert.isAssignable(String.class, Integer.class, (String) null);
+	}
+
+	@Test
+	public void isAssignableWithTypeMismatchAndCustomMessage() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage("enigma: class java.lang.Integer");
+		Assert.isAssignable(String.class, Integer.class, "enigma");
+	}
+
+	@Test
+	public void state() {
+		Assert.state(true, "enigma");
+	}
+
+	@Test
+	public void stateWithFalseExpression() {
+		thrown.expect(IllegalStateException.class);
+		thrown.expectMessage("enigma");
+		Assert.state(false, "enigma");
 	}
 
 }
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
index 1802678042..206c382b20 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,8 @@ public class OpDec extends Operator {
 
 	public OpDec(int pos, boolean postfix, SpelNodeImpl... operands) {
 		super("--", pos, operands);
-		Assert.notEmpty(operands);
 		this.postfix = postfix;
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
index f7ec295e90..ab75f7b55a 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,8 +43,8 @@ public class OpInc extends Operator {
 
 	public OpInc(int pos, boolean postfix, SpelNodeImpl... operands) {
 		super("++", pos, operands);
-		Assert.notEmpty(operands);
 		this.postfix = postfix;
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
index eeefe40ffb..1fc99b2128 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpPlus.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ public class OpPlus extends Operator {
 
 	public OpPlus(int pos, SpelNodeImpl... operands) {
 		super("+", pos, operands);
-		Assert.notEmpty(operands);
+		Assert.notEmpty(operands, "Operands must not be empty");
 	}
 
 
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
index a47b9a103c..f033519e5a 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Operator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ public abstract class Operator extends SpelNodeImpl {
 	protected String rightActualDescriptor;
 
 
-	public Operator(String payload,int pos,SpelNodeImpl... operands) {
+	public Operator(String payload, int pos, SpelNodeImpl... operands) {
 		super(pos, operands);
 		this.operatorName = payload;
 	}
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
index 600ffda6b5..5de6b4b14e 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -79,6 +79,7 @@ import org.springframework.util.StringUtils;
  * Hand written SpEL parser. Instances are reusable but are not thread-safe.
  *
  * @author Andy Clement
+ * @author Juergen Hoeller
  * @author Phillip Webb
  * @since 3.0
  */
@@ -128,7 +129,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			if (moreTokens()) {
 				throw new SpelParseException(peekToken().startPos, SpelMessage.MORE_INPUT, toString(nextToken()));
 			}
-			Assert.isTrue(this.constructedNodes.isEmpty());
+			Assert.isTrue(this.constructedNodes.isEmpty(), "At least one node expected");
 			return new SpelExpression(expressionString, ast, this.configuration);
 		}
 		catch (InternalParseException ex) {
@@ -232,7 +233,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				if (tk == TokenKind.EQ) {
 					return new OpEQ(pos, expr, rhExpr);
 				}
-				Assert.isTrue(tk == TokenKind.NE);
+				Assert.isTrue(tk == TokenKind.NE, "Not-equals token expected");
 				return new OpNE(pos, expr, rhExpr);
 			}
 
@@ -244,7 +245,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				return new OperatorMatches(toPos(t), expr, rhExpr);
 			}
 
-			Assert.isTrue(tk == TokenKind.BETWEEN);
+			Assert.isTrue(tk == TokenKind.BETWEEN, "Between token expected");
 			return new OperatorBetween(toPos(t), expr, rhExpr);
 		}
 		return expr;
@@ -281,7 +282,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				expr = new OpDivide(toPos(t), expr, rhExpr);
 			}
 			else {
-				Assert.isTrue(t.kind == TokenKind.MOD);
+				Assert.isTrue(t.kind == TokenKind.MOD, "Mod token expected");
 				expr = new OpModulus(toPos(t), expr, rhExpr);
 			}
 		}
@@ -298,7 +299,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return new OperatorPower(toPos(t), expr, rhExpr);
 		}
 
-		if (expr != null && peekToken(TokenKind.INC,TokenKind.DEC)) {
+		if (expr != null && peekToken(TokenKind.INC, TokenKind.DEC)) {
 			Token t = nextToken();  //consume INC/DEC
 			if (t.getKind() == TokenKind.INC) {
 				return new OpInc(toPos(t), true, expr);
@@ -321,7 +322,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			if (t.kind == TokenKind.PLUS) {
 				return new OpPlus(toPos(t), expr);
 			}
-			Assert.isTrue(t.kind == TokenKind.MINUS);
+			Assert.isTrue(t.kind == TokenKind.MINUS, "Minus token expected");
 			return new OpMinus(toPos(t), expr);
 
 		}
@@ -356,7 +357,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	// node : ((DOT dottedNode) | (SAFE_NAVI dottedNode) | nonDottedNode)+;
 	private boolean maybeEatNode() {
 		SpelNodeImpl expr = null;
-		if (peekToken(TokenKind.DOT,TokenKind.SAFE_NAVI)) {
+		if (peekToken(TokenKind.DOT, TokenKind.SAFE_NAVI)) {
 			expr = eatDottedNode();
 		}
 		else {
@@ -770,7 +771,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			// It looks like a constructor reference but is NEW being used as a map key?
 			if (peekToken(TokenKind.RSQUARE)) {
 				// looks like 'NEW]' (so NEW used as map key)
-				push(new PropertyOrFieldReference(false,newToken.data,toPos(newToken)));
+				push(new PropertyOrFieldReference(false, newToken.data ,toPos(newToken)));
 				return true;
 			}
 			SpelNodeImpl possiblyQualifiedConstructorName = eatPossiblyQualifiedId();
@@ -940,7 +941,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return false;
 	}
 
-	private boolean peekToken(TokenKind possible1,TokenKind possible2) {
+	private boolean peekToken(TokenKind possible1, TokenKind possible2) {
 		if (!moreTokens()) {
 			return false;
 		}
@@ -948,12 +949,12 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return (t.kind == possible1 || t.kind == possible2);
 	}
 
-	private boolean peekToken(TokenKind possible1,TokenKind possible2, TokenKind possible3) {
+	private boolean peekToken(TokenKind possible1, TokenKind possible2, TokenKind possible3) {
 		if (!moreTokens()) {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == possible1 || t.kind == possible2 || t.kind == possible3;
+		return (t.kind == possible1 || t.kind == possible2 || t.kind == possible3);
 	}
 
 	private boolean peekIdentifierToken(String identifierString) {
@@ -961,7 +962,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == TokenKind.IDENTIFIER && t.stringValue().equalsIgnoreCase(identifierString);
+		return (t.kind == TokenKind.IDENTIFIER && t.stringValue().equalsIgnoreCase(identifierString));
 	}
 
 	private boolean peekSelectToken() {
@@ -969,8 +970,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			return false;
 		}
 		Token t = peekToken();
-		return t.kind == TokenKind.SELECT || t.kind == TokenKind.SELECT_FIRST
-				|| t.kind == TokenKind.SELECT_LAST;
+		return (t.kind == TokenKind.SELECT || t.kind == TokenKind.SELECT_FIRST || t.kind == TokenKind.SELECT_LAST);
 	}
 
 	private boolean moreTokens() {
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java b/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
index e0408f10db..9a62df8912 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,6 @@ import java.util.List;
 import org.springframework.expression.spel.InternalParseException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.SpelParseException;
-import org.springframework.util.Assert;
 
 /**
  * Lex some input data into a stream of tokens that can then be parsed.
@@ -522,9 +521,9 @@ class Tokenizer {
 	 * Check if this might be a two character token.
 	 */
 	private boolean isTwoCharToken(TokenKind kind) {
-		Assert.isTrue(kind.tokenChars.length == 2);
-		Assert.isTrue(this.toProcess[this.pos] == kind.tokenChars[0]);
-		return this.toProcess[this.pos + 1] == kind.tokenChars[1];
+		return (kind.tokenChars.length == 2 &&
+				this.toProcess[this.pos] == kind.tokenChars[0] &&
+				this.toProcess[this.pos + 1] == kind.tokenChars[1]);
 	}
 
 	/**
diff --git a/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java b/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
index 6687ec1688..cfa205b267 100644
--- a/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
+++ b/spring-jdbc/src/main/java/org/springframework/jdbc/core/ParameterDisposer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2005 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,11 +18,11 @@ package org.springframework.jdbc.core;
 
 /**
  * Interface to be implemented by objects that can close resources
- * allocated by parameters like SqlLobValues.
+ * allocated by parameters like {@code SqlLobValue} objects.
  *
- * <p>Typically implemented by PreparedStatementCreators and
- * PreparedStatementSetters that support DisposableSqlTypeValue
- * objects (e.g. SqlLobValue) as parameters.
+ * <p>Typically implemented by {@code PreparedStatementCreators} and
+ * {@code PreparedStatementSetters} that support {@link DisposableSqlTypeValue}
+ * objects (e.g. {@code SqlLobValue}) as parameters.
  *
  * @author Thomas Risberg
  * @author Juergen Hoeller
@@ -38,9 +38,9 @@ public interface ParameterDisposer {
 	 * Close the resources allocated by parameters that the implementing
 	 * object holds, for example in case of a DisposableSqlTypeValue
 	 * (like a SqlLobValue).
-	 * @see DisposableSqlTypeValue#cleanup
-	 * @see org.springframework.jdbc.core.support.SqlLobValue#cleanup
+	 * @see DisposableSqlTypeValue#cleanup()
+	 * @see org.springframework.jdbc.core.support.SqlLobValue#cleanup()
 	 */
-	public void cleanupParameters();
+	void cleanupParameters();
 
 }
diff --git a/spring-jms/src/main/java/org/springframework/jms/core/JmsMessagingTemplate.java b/spring-jms/src/main/java/org/springframework/jms/core/JmsMessagingTemplate.java
index 7a22c041a1..43fcf0eb36 100644
--- a/spring-jms/src/main/java/org/springframework/jms/core/JmsMessagingTemplate.java
+++ b/spring-jms/src/main/java/org/springframework/jms/core/JmsMessagingTemplate.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -73,7 +73,7 @@ public class JmsMessagingTemplate extends AbstractMessagingTemplate<Destination>
 	 * Create a {@code JmsMessagingTemplate} instance with the {@link JmsTemplate} to use.
 	 */
 	public JmsMessagingTemplate(JmsTemplate jmsTemplate) {
-		Assert.notNull("JmsTemplate must not be null");
+		Assert.notNull(jmsTemplate, "JmsTemplate must not be null");
 		this.jmsTemplate = jmsTemplate;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
index a09214e90f..3fb594ebb2 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java
@@ -94,7 +94,9 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 			throws Exception {
 
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		Assert.notNull(handler, "No handler for return value type [" + returnType.getParameterType().getName() + "]");
+		if (handler == null) {
+			throw new IllegalStateException("No handler for return value type: " + returnType.getParameterType());
+		}
 		if (logger.isTraceEnabled()) {
 			logger.trace("Processing return value with " + handler);
 		}
@@ -104,14 +106,15 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 	@Override
 	public boolean isAsyncReturnValue(Object returnValue, MethodParameter returnType) {
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		return (handler != null && handler instanceof AsyncHandlerMethodReturnValueHandler &&
+		return (handler instanceof AsyncHandlerMethodReturnValueHandler &&
 				((AsyncHandlerMethodReturnValueHandler) handler).isAsyncReturnValue(returnValue, returnType));
 	}
 
 	@Override
 	public ListenableFuture<?> toListenableFuture(Object returnValue, MethodParameter returnType) {
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
-		Assert.isTrue(handler != null && handler instanceof AsyncHandlerMethodReturnValueHandler);
+		Assert.state(handler instanceof AsyncHandlerMethodReturnValueHandler,
+				"AsyncHandlerMethodReturnValueHandler required");
 		return ((AsyncHandlerMethodReturnValueHandler) handler).toListenableFuture(returnValue, returnType);
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
index 493f1224b2..0088adb7d8 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpMessagingTemplate.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,10 +58,10 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate<String
 
 	/**
 	 * Create a new {@link SimpMessagingTemplate} instance.
-	 * @param messageChannel the message channel (must not be {@code null})
+	 * @param messageChannel the message channel (never {@code null})
 	 */
 	public SimpMessagingTemplate(MessageChannel messageChannel) {
-		Assert.notNull(messageChannel, "'messageChannel' must not be null");
+		Assert.notNull(messageChannel, "MessageChannel must not be null");
 		this.messageChannel = messageChannel;
 	}
 
@@ -79,8 +79,8 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate<String
 	 * @see org.springframework.messaging.simp.user.UserDestinationMessageHandler
 	 */
 	public void setUserDestinationPrefix(String prefix) {
-		Assert.hasText(prefix, "'destinationPrefix' must not be empty");
-		this.destinationPrefix = prefix.endsWith("/") ? prefix : prefix + "/";
+		Assert.hasText(prefix, "User destination prefix must not be empty");
+		this.destinationPrefix = (prefix.endsWith("/") ? prefix : prefix + "/");
 
 	}
 
@@ -135,7 +135,7 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate<String
 	 */
 	@Override
 	public void send(Message<?> message) {
-		Assert.notNull(message, "'message' is required");
+		Assert.notNull(message, "Message is required");
 		String destination = SimpMessageHeaderAccessor.getDestination(message.getHeaders());
 		if (destination != null) {
 			sendInternal(message);
@@ -178,7 +178,7 @@ public class SimpMessagingTemplate extends AbstractMessageSendingTemplate<String
 
 	private void sendInternal(Message<?> message) {
 		String destination = SimpMessageHeaderAccessor.getDestination(message.getHeaders());
-		Assert.notNull(destination);
+		Assert.notNull(destination, "Destination header required");
 
 		long timeout = this.sendTimeout;
 		boolean sent = (timeout >= 0 ? this.messageChannel.send(message, timeout) : this.messageChannel.send(message));
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
index 8116540280..814ab49527 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -487,7 +487,7 @@ public class SimpAnnotationMethodMessageHandler extends AbstractMethodMessageHan
 			Map<String, String> vars = getPathMatcher().extractUriTemplateVariables(pattern, lookupDestination);
 			if (!CollectionUtils.isEmpty(vars)) {
 				MessageHeaderAccessor mha = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
-				Assert.state(mha != null && mha.isMutable());
+				Assert.state(mha != null && mha.isMutable(), "Mutable MessageHeaderAccessor required");
 				mha.setHeader(DestinationVariableMethodArgumentResolver.DESTINATION_TEMPLATE_VARIABLES_HEADER, vars);
 			}
 		}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
index eef8f689b2..c19ac1531d 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.messaging.simp.broker;
 
 import java.security.Principal;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -174,7 +175,9 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 	 * @since 4.2
 	 */
 	public void setHeartbeatValue(long[] heartbeat) {
-		Assert.notNull(heartbeat);
+		if (heartbeat == null || heartbeat.length != 2 || heartbeat[0] < 0 || heartbeat[1] < 0) {
+			throw new IllegalArgumentException("Invalid heart-beat: " + Arrays.toString(heartbeat));
+		}
 		this.heartbeatValue = heartbeat;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
index 4e08188c43..fa1131db1b 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractMessageBrokerConfiguration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -317,14 +317,14 @@ public abstract class AbstractMessageBrokerConfiguration implements ApplicationC
 			return new NoOpMessageHandler();
 		}
 		SimpUserRegistry userRegistry = userRegistry();
-		Assert.isInstanceOf(MultiServerUserRegistry.class, userRegistry);
+		Assert.isInstanceOf(MultiServerUserRegistry.class, userRegistry, "MultiServerUserRegistry required");
 		return new UserRegistryMessageHandler((MultiServerUserRegistry) userRegistry,
 				brokerMessagingTemplate(), getBrokerRegistry().getUserRegistryBroadcast(),
 				messageBrokerTaskScheduler());
 	}
 
 	// Expose alias for 4.1 compatibility
-	@Bean(name={"messageBrokerTaskScheduler", "messageBrokerSockJsTaskScheduler"})
+	@Bean(name = {"messageBrokerTaskScheduler", "messageBrokerSockJsTaskScheduler"})
 	public ThreadPoolTaskScheduler messageBrokerTaskScheduler() {
 		ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
 		scheduler.setThreadNamePrefix("MessageBroker-");
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
index 3c8dd759d2..5267b0ffff 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/MessageBrokerRegistry.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,8 +55,8 @@ public class MessageBrokerRegistry {
 
 
 	public MessageBrokerRegistry(SubscribableChannel clientInboundChannel, MessageChannel clientOutboundChannel) {
-		Assert.notNull(clientInboundChannel);
-		Assert.notNull(clientOutboundChannel);
+		Assert.notNull(clientInboundChannel, "Inbound channel must not be null");
+		Assert.notNull(clientOutboundChannel, "Outbound channel must not be null");
 		this.clientInboundChannel = clientInboundChannel;
 		this.clientOutboundChannel = clientOutboundChannel;
 	}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
index aab003e101..8deeb3f4de 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -175,7 +175,7 @@ public class DefaultStompSession implements ConnectionHandlingStompSession {
 	 * <p>By default set to 15,000 (15 seconds).
 	 */
 	public void setReceiptTimeLimit(long receiptTimeLimit) {
-		Assert.isTrue(receiptTimeLimit > 0);
+		Assert.isTrue(receiptTimeLimit > 0, "Receipt time limit must be larger than zero");
 		this.receiptTimeLimit = receiptTimeLimit;
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
index bedbeb089e..b1c48da346 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -131,7 +131,7 @@ public abstract class StompClientSupport {
 	 * <p>By default set to 15,000 (15 seconds).
 	 */
 	public void setReceiptTimeLimit(long receiptTimeLimit) {
-		Assert.isTrue(receiptTimeLimit > 0);
+		Assert.isTrue(receiptTimeLimit > 0, "Receipt time limit must be larger than zero");
 		this.receiptTimeLimit = receiptTimeLimit;
 	}
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/Reactor2TcpStompClientTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/Reactor2TcpStompClientTests.java
index 94bfce4be3..94f4642e81 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/Reactor2TcpStompClientTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/Reactor2TcpStompClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -159,7 +159,7 @@ public class Reactor2TcpStompClientTests {
 		private final List<String> received = new ArrayList<>();
 
 		public ConsumingHandler(String... topics) {
-			Assert.notEmpty(topics);
+			Assert.notEmpty(topics, "Topics must not be empty");
 			this.topics = Arrays.asList(topics);
 			this.subscriptionLatch = new CountDownLatch(this.topics.size());
 		}
@@ -168,7 +168,6 @@ public class Reactor2TcpStompClientTests {
 			return this.received;
 		}
 
-
 		@Override
 		public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
 			for (String topic : this.topics) {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
index 62e0407cb6..38fdb93a15 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -401,7 +401,6 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 		}
 
 		public static MessageExchangeBuilder disconnectWithReceipt(String sessionId, String receiptId) {
-
 			StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.DISCONNECT);
 			headers.setSessionId(sessionId);
 			headers.setReceipt(receiptId);
@@ -413,7 +412,7 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 		}
 
 		public MessageExchangeBuilder andExpectMessage(String sessionId, String subscriptionId) {
-			Assert.isTrue(SimpMessageType.MESSAGE.equals(headers.getMessageType()));
+			Assert.state(SimpMessageType.MESSAGE.equals(this.headers.getMessageType()), "MESSAGE type expected");
 			String destination = this.headers.getDestination();
 			Object payload = this.message.getPayload();
 			this.expected.add(new StompMessageFrameMessageMatcher(sessionId, subscriptionId, destination, payload));
@@ -422,7 +421,7 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 
 		public MessageExchangeBuilder andExpectError() {
 			String sessionId = this.headers.getSessionId();
-			Assert.notNull(sessionId, "No sessionId to match the ERROR frame to");
+			Assert.state(sessionId != null, "No sessionId to match the ERROR frame to");
 			return andExpectError(sessionId);
 		}
 
diff --git a/spring-orm-hibernate5/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java b/spring-orm-hibernate5/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
index 7f3d2e28a7..fafa3f6b78 100644
--- a/spring-orm-hibernate5/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
+++ b/spring-orm-hibernate5/src/main/java/org/springframework/orm/hibernate5/SessionFactoryUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -110,7 +110,7 @@ public abstract class SessionFactoryUtils {
 			}
 		}
 		// Check that it is the Hibernate FlushMode type, not JPA's...
-		Assert.state(FlushMode.class == getFlushMode.getReturnType());
+		Assert.state(FlushMode.class == getFlushMode.getReturnType(), "Could not find Hibernate getFlushMode method");
 	}
 
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java b/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
index f4401ae298..f56f3586b3 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/AbstractEntityManagerFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -135,7 +135,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see javax.persistence.Persistence
 	 */
 	public void setPersistenceProviderClass(Class<? extends PersistenceProvider> persistenceProviderClass) {
-		Assert.isAssignable(PersistenceProvider.class, persistenceProviderClass);
 		this.persistenceProvider = BeanUtils.instantiateClass(persistenceProviderClass);
 	}
 
@@ -217,7 +216,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see JpaVendorAdapter#getEntityManagerFactoryInterface()
 	 */
 	public void setEntityManagerFactoryInterface(Class<? extends EntityManagerFactory> emfInterface) {
-		Assert.isAssignable(EntityManagerFactory.class, emfInterface);
 		this.entityManagerFactoryInterface = emfInterface;
 	}
 
@@ -231,7 +229,6 @@ public abstract class AbstractEntityManagerFactoryBean implements
 	 * @see EntityManagerFactoryInfo#getEntityManagerInterface()
 	 */
 	public void setEntityManagerInterface(Class<? extends EntityManager> emInterface) {
-		Assert.isAssignable(EntityManager.class, emInterface);
 		this.entityManagerInterface = emInterface;
 	}
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java b/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
index c6595279de..4c5b44592d 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/support/SharedEntityManagerBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -68,7 +68,6 @@ public class SharedEntityManagerBean extends EntityManagerFactoryAccessor
 	 */
 	public void setEntityManagerInterface(Class<? extends EntityManager> entityManagerInterface) {
 		Assert.notNull(entityManagerInterface, "'entityManagerInterface' must not be null");
-		Assert.isAssignable(EntityManager.class, entityManagerInterface);
 		this.entityManagerInterface = entityManagerInterface;
 	}
 
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java b/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
index c089b42561..809923b882 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -122,7 +122,7 @@ public class HibernateJpaDialect extends DefaultJpaDialect {
 			}
 		}
 		// Check that it is the Hibernate FlushMode type, not JPA's...
-		Assert.state(FlushMode.class == getFlushMode.getReturnType());
+		Assert.state(FlushMode.class == getFlushMode.getReturnType(), "Could not find Hibernate getFlushMode method");
 	}
 
 
diff --git a/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java b/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
index 7ce47f58c4..2c738767e7 100644
--- a/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
+++ b/spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java
@@ -79,7 +79,6 @@ import org.springframework.oxm.UncategorizedMappingException;
 import org.springframework.oxm.UnmarshallingFailureException;
 import org.springframework.oxm.XmlMappingException;
 import org.springframework.oxm.support.AbstractMarshaller;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -114,7 +113,7 @@ import org.springframework.util.xml.StaxUtils;
  * @author Juergen Hoeller
  * @since 3.0
  */
-public class XStreamMarshaller extends AbstractMarshaller implements InitializingBean, BeanClassLoaderAware {
+public class XStreamMarshaller extends AbstractMarshaller implements BeanClassLoaderAware, InitializingBean {
 
 	/**
 	 * The default encoding used for stream access: UTF-8.
@@ -130,7 +129,7 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 
 	private Mapper mapper;
 
-	private Class<?>[] mapperWrappers;
+	private Class<? extends MapperWrapper>[] mapperWrappers;
 
 	private ConverterLookup converterLookup = new DefaultConverterLookup();
 
@@ -210,7 +209,8 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 	 * of type {@link Mapper} or {@link MapperWrapper}.
 	 * @since 4.0
 	 */
-	public void setMapperWrappers(Class<?>... mapperWrappers) {
+	@SuppressWarnings("unchecked")
+	public void setMapperWrappers(Class<? extends MapperWrapper>... mapperWrappers) {
 		this.mapperWrappers = mapperWrappers;
 	}
 
@@ -413,9 +413,8 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 			protected MapperWrapper wrapMapper(MapperWrapper next) {
 				MapperWrapper mapperToWrap = next;
 				if (mapperWrappers != null) {
-					for (Class<?> mapperWrapper : mapperWrappers) {
-						Assert.isAssignable(MapperWrapper.class, mapperWrapper);
-						Constructor<?> ctor;
+					for (Class<? extends MapperWrapper> mapperWrapper : mapperWrappers) {
+						Constructor<? extends MapperWrapper> ctor;
 						try {
 							ctor = mapperWrapper.getConstructor(Mapper.class);
 						}
@@ -428,9 +427,9 @@ public class XStreamMarshaller extends AbstractMarshaller implements Initializin
 							}
 						}
 						try {
-							mapperToWrap = (MapperWrapper) ctor.newInstance(mapperToWrap);
+							mapperToWrap = ctor.newInstance(mapperToWrap);
 						}
-						catch (Exception ex) {
+						catch (Throwable ex) {
 							throw new IllegalStateException("Failed to construct MapperWrapper: " + mapperWrapper);
 						}
 					}
diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java b/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
index ae4e8b8b43..12a58a77d2 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,7 +61,7 @@ public class MockAsyncContext implements AsyncContext {
 
 
 	public void addDispatchHandler(Runnable handler) {
-		Assert.notNull(handler);
+		Assert.notNull(handler, "Dispatch handler must not be null");
 		this.dispatchHandlers.add(handler);
 	}
 
@@ -77,7 +77,7 @@ public class MockAsyncContext implements AsyncContext {
 
 	@Override
 	public boolean hasOriginalRequestAndResponse() {
-		return (this.request instanceof MockHttpServletRequest) && (this.response instanceof MockHttpServletResponse);
+		return (this.request instanceof MockHttpServletRequest && this.response instanceof MockHttpServletResponse);
 	}
 
 	@Override
diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java b/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
index 0e95d460b5..1f7d18c23a 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockPageContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -356,12 +356,12 @@ public class MockPageContext extends PageContext {
 	}
 
 	public byte[] getContentAsByteArray() {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsByteArray();
 	}
 
 	public String getContentAsString() throws UnsupportedEncodingException {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsString();
 	}
 
diff --git a/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java b/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
index dbcf3852de..89d91f1e62 100644
--- a/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
+++ b/spring-test/src/main/java/org/springframework/test/web/client/SimpleRequestExpectationManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ public class SimpleRequestExpectationManager extends AbstractRequestExpectationM
 
 	@Override
 	protected void afterExpectationsDeclared() {
-		Assert.state(this.expectationIterator == null);
+		Assert.state(this.expectationIterator == null, "Expectations already declared");
 		this.expectationIterator = getExpectations().iterator();
 	}
 
diff --git a/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java b/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
index f194c41a45..62a9ad6588 100644
--- a/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
+++ b/spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/FrameworkExtensionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,10 +41,10 @@ import static org.springframework.test.web.servlet.setup.MockMvcBuilders.*;
 /**
  * Demonstrates use of SPI extension points:
  * <ul>
- * 	<li> {@link org.springframework.test.web.servlet.request.RequestPostProcessor}
- * 	for extending request building with custom methods.
- * 	<li> {@link org.springframework.test.web.servlet.setup.MockMvcConfigurer
- * 	MockMvcConfigurer} for extending MockMvc building with some automatic setup.
+ * <li> {@link org.springframework.test.web.servlet.request.RequestPostProcessor}
+ * for extending request building with custom methods.
+ * <li> {@link org.springframework.test.web.servlet.setup.MockMvcConfigurer
+ * MockMvcConfigurer} for extending MockMvc building with some automatic setup.
  * </ul>
  *
  * @author Rossen Stoyanchev
@@ -106,6 +106,7 @@ public class FrameworkExtensionTests {
 		}
 	}
 
+
 	/**
 	 * Test {@code MockMvcConfigurer}.
 	 */
@@ -126,6 +127,7 @@ public class FrameworkExtensionTests {
 		}
 	}
 
+
 	@Controller
 	@RequestMapping("/")
 	private static class SampleController {
@@ -133,16 +135,16 @@ public class FrameworkExtensionTests {
 		@RequestMapping(headers = "Foo")
 		@ResponseBody
 		public String handleFoo(Principal principal) {
-			Assert.isTrue(principal != null);
+			Assert.notNull(principal, "Principal must not be null");
 			return "Foo";
 		}
 
 		@RequestMapping(headers = "Bar")
 		@ResponseBody
 		public String handleBar(Principal principal) {
-			Assert.isTrue(principal != null);
+			Assert.notNull(principal, "Principal must not be null");
 			return "Bar";
 		}
 	}
 
-}
\ No newline at end of file
+}
diff --git a/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java b/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
index 2a81efc182..d4b7d3084e 100644
--- a/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
+++ b/spring-tx/src/main/java/org/springframework/jca/support/ResourceAdapterFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,15 +26,14 @@ import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.util.Assert;
 
 /**
  * {@link org.springframework.beans.factory.FactoryBean} that bootstraps
- * the specified JCA 1.5 {@link javax.resource.spi.ResourceAdapter},
+ * the specified JCA 1.7 {@link javax.resource.spi.ResourceAdapter},
  * starting it with a local {@link javax.resource.spi.BootstrapContext}
  * and exposing it for bean references. It will also stop the ResourceAdapter
  * on context shutdown. This corresponds to 'non-managed' bootstrap in a
- * local environment, according to the JCA 1.5 specification.
+ * local environment, according to the JCA 1.7 specification.
  *
  * <p>This is essentially an adapter for bean-style bootstrapping of a
  * JCA ResourceAdapter, allowing the BootstrapContext or its elements
@@ -66,9 +65,8 @@ public class ResourceAdapterFactoryBean implements FactoryBean<ResourceAdapter>,
 	 * through the "resourceAdapter" property.
 	 * @see #setResourceAdapter
 	 */
-	public void setResourceAdapterClass(Class<?> resourceAdapterClass) {
-		Assert.isAssignable(ResourceAdapter.class, resourceAdapterClass);
-		this.resourceAdapter = (ResourceAdapter) BeanUtils.instantiateClass(resourceAdapterClass);
+	public void setResourceAdapterClass(Class<? extends ResourceAdapter> resourceAdapterClass) {
+		this.resourceAdapter = BeanUtils.instantiateClass(resourceAdapterClass);
 	}
 
 	/**
diff --git a/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java b/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
index bf982d6e24..3aff0c9221 100644
--- a/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
+++ b/spring-web/src/main/java/org/springframework/http/client/SimpleClientHttpRequestFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -177,7 +177,9 @@ public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory,
 	 */
 	protected HttpURLConnection openConnection(URL url, Proxy proxy) throws IOException {
 		URLConnection urlConnection = (proxy != null ? url.openConnection(proxy) : url.openConnection());
-		Assert.isInstanceOf(HttpURLConnection.class, urlConnection);
+		if (!HttpURLConnection.class.isInstance(urlConnection)) {
+			throw new IllegalStateException("HttpURLConnection required for [" + url + "] but got: " + urlConnection);
+		}
 		return (HttpURLConnection) urlConnection;
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
index 39eb13ef67..a829385634 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -60,16 +60,17 @@ public class MappingJackson2XmlHttpMessageConverter extends AbstractJackson2Http
 		super(objectMapper, new MediaType("application", "xml"),
 				new MediaType("text", "xml"),
 				new MediaType("application", "*+xml"));
-		Assert.isAssignable(XmlMapper.class, objectMapper.getClass());
+		Assert.isInstanceOf(XmlMapper.class, objectMapper, "XmlMapper required");
 	}
 
+
 	/**
 	 * {@inheritDoc}
-	 * The {@code objectMapper} parameter must be a {@link XmlMapper} instance.
+	 * The {@code ObjectMapper} parameter must be a {@link XmlMapper} instance.
 	 */
 	@Override
 	public void setObjectMapper(ObjectMapper objectMapper) {
-		Assert.isAssignable(XmlMapper.class, objectMapper.getClass());
+		Assert.isInstanceOf(XmlMapper.class, objectMapper, "XmlMapper required");
 		super.setObjectMapper(objectMapper);
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java b/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
index 660044b8e8..05ba9d94a2 100644
--- a/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
+++ b/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -180,7 +180,9 @@ public class ServletServerHttpRequest implements ServerHttpRequest {
 	@Override
 	public ServerHttpAsyncRequestControl getAsyncRequestControl(ServerHttpResponse response) {
 		if (this.asyncRequestControl == null) {
-			Assert.isInstanceOf(ServletServerHttpResponse.class, response);
+			if (!ServletServerHttpResponse.class.isInstance(response)) {
+				throw new IllegalArgumentException("Response must be a ServletServerHttpResponse: " + response.getClass());
+			}
 			ServletServerHttpResponse servletServerResponse = (ServletServerHttpResponse) response;
 			this.asyncRequestControl = new ServletServerHttpAsyncRequestControl(this, servletServerResponse);
 		}
diff --git a/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java b/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
index 000b637964..04727bd4de 100644
--- a/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
+++ b/spring-web/src/main/java/org/springframework/web/accept/PathExtensionContentNegotiationStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -140,15 +140,15 @@ public class PathExtensionContentNegotiationStrategy extends AbstractMappingCont
 
 	/**
 	 * A public method exposing the knowledge of the path extension strategy to
-	 * resolve file extensions to a MediaType in this case for a given
+	 * resolve file extensions to a {@link MediaType} in this case for a given
 	 * {@link Resource}. The method first looks up any explicitly registered
 	 * file extensions first and then falls back on JAF if available.
 	 * @param resource the resource to look up
-	 * @return the MediaType for the extension or {@code null}.
+	 * @return the MediaType for the extension, or {@code null} if none found
 	 * @since 4.3
 	 */
 	public MediaType getMediaTypeForResource(Resource resource) {
-		Assert.notNull(resource);
+		Assert.notNull(resource, "Resource must not be null");
 		MediaType mediaType = null;
 		String filename = resource.getFilename();
 		String extension = StringUtils.getFilenameExtension(filename);
diff --git a/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java b/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
index cb274152e4..9b4c91add0 100644
--- a/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
+++ b/spring-web/src/main/java/org/springframework/web/bind/UnsatisfiedServletRequestParameterException.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,7 +64,7 @@ public class UnsatisfiedServletRequestParameterException extends ServletRequestB
 			Map<String, String[]> actualParams) {
 
 		super("");
-		Assert.isTrue(!CollectionUtils.isEmpty(paramConditions));
+		Assert.notEmpty(paramConditions, "Parameter conditions must not be empty");
 		this.paramConditions = paramConditions;
 		this.actualParams = actualParams;
 	}
diff --git a/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java b/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
index 595d2908c0..4a7656f18f 100644
--- a/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
+++ b/spring-web/src/main/java/org/springframework/web/context/ContextLoader.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -40,7 +40,6 @@ import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.support.PropertiesLoaderUtils;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -517,7 +516,10 @@ public class ContextLoader {
 	private Class<ApplicationContextInitializer<ConfigurableApplicationContext>> loadInitializerClass(String className) {
 		try {
 			Class<?> clazz = ClassUtils.forName(className, ClassUtils.getDefaultClassLoader());
-			Assert.isAssignable(ApplicationContextInitializer.class, clazz);
+			if (!ApplicationContextInitializer.class.isAssignableFrom(clazz)) {
+				throw new ApplicationContextException(
+						"Initializer class does not implement ApplicationContextInitializer interface: " + clazz);
+			}
 			return (Class<ApplicationContextInitializer<ConfigurableApplicationContext>>) clazz;
 		}
 		catch (ClassNotFoundException ex) {
diff --git a/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java b/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
index 758266b34c..ce07354272 100644
--- a/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
+++ b/spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java
@@ -793,7 +793,7 @@ final class HierarchicalUriComponents extends UriComponents {
 		private final List<PathComponent> pathComponents;
 
 		public PathComponentComposite(List<PathComponent> pathComponents) {
-			Assert.notNull(pathComponents);
+			Assert.notNull(pathComponents, "PathComponent List must not be null");
 			this.pathComponents = pathComponents;
 		}
 
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
index 7fb4f8ec95..a23f44e8ab 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,7 +61,7 @@ public class MockAsyncContext implements AsyncContext {
 
 
 	public void addDispatchHandler(Runnable handler) {
-		Assert.notNull(handler);
+		Assert.notNull(handler, "Dispatch handler must not be null");
 		this.dispatchHandlers.add(handler);
 	}
 
@@ -77,7 +77,7 @@ public class MockAsyncContext implements AsyncContext {
 
 	@Override
 	public boolean hasOriginalRequestAndResponse() {
-		return (this.request instanceof MockHttpServletRequest) && (this.response instanceof MockHttpServletResponse);
+		return (this.request instanceof MockHttpServletRequest && this.response instanceof MockHttpServletResponse);
 	}
 
 	@Override
@@ -112,8 +112,8 @@ public class MockAsyncContext implements AsyncContext {
 			try {
 				listener.onComplete(new AsyncEvent(this, this.request, this.response));
 			}
-			catch (IOException e) {
-				throw new IllegalStateException("AsyncListener failure", e);
+			catch (IOException ex) {
+				throw new IllegalStateException("AsyncListener failure", ex);
 			}
 		}
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
index 95acca3f91..76bef2ab2a 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -356,12 +356,12 @@ public class MockPageContext extends PageContext {
 	}
 
 	public byte[] getContentAsByteArray() {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsByteArray();
 	}
 
 	public String getContentAsString() throws UnsupportedEncodingException {
-		Assert.isTrue(this.response instanceof MockHttpServletResponse);
+		Assert.state(this.response instanceof MockHttpServletResponse, "MockHttpServletResponse required");
 		return ((MockHttpServletResponse) this.response).getContentAsString();
 	}
 
diff --git a/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java b/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
index 09f3700a3c..aa30b5cac1 100644
--- a/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
+++ b/spring-web/src/test/java/org/springframework/web/util/DefaultUriTemplateHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.web.util;
 
 import java.net.URI;
@@ -21,13 +22,14 @@ import java.util.Map;
 
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 /**
  * Unit tests for {@link DefaultUriTemplateHandler}.
  *
  * @author Rossen Stoyanchev
  */
+@SuppressWarnings("deprecation")
 public class DefaultUriTemplateHandlerTests {
 
 	private final DefaultUriTemplateHandler handler = new DefaultUriTemplateHandler();
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
index 5460207d1b..8822f36a3b 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,7 @@ import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceEditor;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.support.ServletContextResourceLoader;
 import org.springframework.web.context.support.StandardServletEnvironment;
@@ -78,8 +79,7 @@ import org.springframework.web.context.support.StandardServletEnvironment;
  * @see #doPost
  */
 @SuppressWarnings("serial")
-public abstract class HttpServletBean extends HttpServlet
-		implements EnvironmentCapable, EnvironmentAware {
+public abstract class HttpServletBean extends HttpServlet implements EnvironmentCapable, EnvironmentAware {
 
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
@@ -128,7 +128,9 @@ public abstract class HttpServletBean extends HttpServlet
 			bw.setPropertyValues(pvs, true);
 		}
 		catch (BeansException ex) {
-			logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
+			if (logger.isErrorEnabled()) {
+				logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
+			}
 			throw ex;
 		}
 
@@ -190,7 +192,7 @@ public abstract class HttpServletBean extends HttpServlet
 	 */
 	@Override
 	public void setEnvironment(Environment environment) {
-		Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
+		Assert.isInstanceOf(ConfigurableEnvironment.class, environment, "ConfigurableEnvironment required");
 		this.environment = (ConfigurableEnvironment) environment;
 	}
 
@@ -231,12 +233,12 @@ public abstract class HttpServletBean extends HttpServlet
 		public ServletConfigPropertyValues(ServletConfig config, Set<String> requiredProperties)
 			throws ServletException {
 
-			Set<String> missingProps = (requiredProperties != null && !requiredProperties.isEmpty()) ?
-					new HashSet<String>(requiredProperties) : null;
+			Set<String> missingProps = (requiredProperties != null && !requiredProperties.isEmpty() ?
+					new HashSet<String>(requiredProperties) : null);
 
-			Enumeration<String> en = config.getInitParameterNames();
-			while (en.hasMoreElements()) {
-				String property = en.nextElement();
+			Enumeration<String> paramNames = config.getInitParameterNames();
+			while (paramNames.hasMoreElements()) {
+				String property = paramNames.nextElement();
 				Object value = config.getInitParameter(property);
 				addPropertyValue(new PropertyValue(property, value));
 				if (missingProps != null) {
@@ -245,7 +247,7 @@ public abstract class HttpServletBean extends HttpServlet
 			}
 
 			// Fail if we are still missing properties.
-			if (missingProps != null && missingProps.size() > 0) {
+			if (!CollectionUtils.isEmpty(missingProps)) {
 				throw new ServletException(
 					"Initialization from ServletConfig for servlet '" + config.getServletName() +
 					"' failed; the following required properties were missing: " +
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
index 65a8db2611..f471b36aca 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -681,8 +681,8 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 		private final String mappingName;
 
 		public MappingRegistration(T mapping, HandlerMethod handlerMethod, List<String> directUrls, String mappingName) {
-			Assert.notNull(mapping);
-			Assert.notNull(handlerMethod);
+			Assert.notNull(mapping, "Mapping must not be null");
+			Assert.notNull(handlerMethod, "HandlerMethod must not be null");
 			this.mapping = mapping;
 			this.handlerMethod = handlerMethod;
 			this.directUrls = (directUrls != null ? directUrls : Collections.<String>emptyList());
@@ -747,7 +747,7 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 	private static class EmptyHandler {
 
 		public void handle() {
-			throw new UnsupportedOperationException("not implemented");
+			throw new UnsupportedOperationException("Not implemented");
 		}
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
index 51bed445cf..16a120cb4f 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -170,6 +170,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 			validateHandler(handler, request);
 			return buildPathExposingHandler(handler, urlPath, urlPath, null);
 		}
+
 		// Pattern match?
 		List<String> matchingPatterns = new ArrayList<String>();
 		for (String registeredPattern : this.handlerMap.keySet()) {
@@ -182,20 +183,26 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 				}
 			}
 		}
-		String bestPatternMatch = null;
+
+		String bestMatch = null;
 		Comparator<String> patternComparator = getPathMatcher().getPatternComparator(urlPath);
 		if (!matchingPatterns.isEmpty()) {
 			Collections.sort(matchingPatterns, patternComparator);
 			if (logger.isDebugEnabled()) {
 				logger.debug("Matching patterns for request [" + urlPath + "] are " + matchingPatterns);
 			}
-			bestPatternMatch = matchingPatterns.get(0);
+			bestMatch = matchingPatterns.get(0);
 		}
-		if (bestPatternMatch != null) {
-			handler = this.handlerMap.get(bestPatternMatch);
+		if (bestMatch != null) {
+			handler = this.handlerMap.get(bestMatch);
 			if (handler == null) {
-				Assert.isTrue(bestPatternMatch.endsWith("/"));
-				handler = this.handlerMap.get(bestPatternMatch.substring(0, bestPatternMatch.length() - 1));
+				if (bestMatch.endsWith("/")) {
+					handler = this.handlerMap.get(bestMatch.substring(0, bestMatch.length() - 1));
+				}
+				if (handler == null) {
+					throw new IllegalStateException(
+							"Could not find handler for best pattern match [" + bestMatch + "]");
+				}
 			}
 			// Bean name or resolved handler?
 			if (handler instanceof String) {
@@ -203,13 +210,13 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 				handler = getApplicationContext().getBean(handlerName);
 			}
 			validateHandler(handler, request);
-			String pathWithinMapping = getPathMatcher().extractPathWithinPattern(bestPatternMatch, urlPath);
+			String pathWithinMapping = getPathMatcher().extractPathWithinPattern(bestMatch, urlPath);
 
 			// There might be multiple 'best patterns', let's make sure we have the correct URI template variables
 			// for all of them
 			Map<String, String> uriTemplateVariables = new LinkedHashMap<String, String>();
 			for (String matchingPattern : matchingPatterns) {
-				if (patternComparator.compare(bestPatternMatch, matchingPattern) == 0) {
+				if (patternComparator.compare(bestMatch, matchingPattern) == 0) {
 					Map<String, String> vars = getPathMatcher().extractUriTemplateVariables(matchingPattern, urlPath);
 					Map<String, String> decodedVars = getUrlPathHelper().decodePathVariables(request, vars);
 					uriTemplateVariables.putAll(decodedVars);
@@ -218,8 +225,9 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 			if (logger.isDebugEnabled()) {
 				logger.debug("URI Template variables for request [" + urlPath + "] are " + uriTemplateVariables);
 			}
-			return buildPathExposingHandler(handler, bestPatternMatch, pathWithinMapping, uriTemplateVariables);
+			return buildPathExposingHandler(handler, bestMatch, pathWithinMapping, uriTemplateVariables);
 		}
+
 		// No handler found...
 		return null;
 	}
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
index 789606dc63..906495956b 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/DeferredResultMethodReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -96,7 +96,10 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 		}
 
 		DeferredResultAdapter adapter = getAdapterFor(returnValue.getClass());
-		Assert.notNull(adapter);
+		if (adapter == null) {
+			throw new IllegalStateException(
+					"Could not find DeferredResultAdapter for return value type: " + returnValue.getClass());
+		}
 		DeferredResult<?> result = adapter.adaptToDeferredResult(returnValue);
 		WebAsyncUtils.getAsyncManager(webRequest).startDeferredResultProcessing(result, mavContainer);
 	}
@@ -109,7 +112,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult<?> adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(DeferredResult.class, returnValue);
+			Assert.isInstanceOf(DeferredResult.class, returnValue, "DeferredResult expected");
 			return (DeferredResult<?>) returnValue;
 		}
 	}
@@ -122,7 +125,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult<?> adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(ListenableFuture.class, returnValue);
+			Assert.isInstanceOf(ListenableFuture.class, returnValue, "ListenableFuture expected");
 			final DeferredResult<Object> result = new DeferredResult<Object>();
 			((ListenableFuture<?>) returnValue).addCallback(new ListenableFutureCallback<Object>() {
 				@Override
@@ -147,7 +150,7 @@ public class DeferredResultMethodReturnValueHandler implements AsyncHandlerMetho
 
 		@Override
 		public DeferredResult<?> adaptToDeferredResult(Object returnValue) {
-			Assert.isInstanceOf(CompletionStage.class, returnValue);
+			Assert.isInstanceOf(CompletionStage.class, returnValue, "CompletionStage expected");
 			final DeferredResult<Object> result = new DeferredResult<Object>();
 			@SuppressWarnings("unchecked")
 			CompletionStage<?> future = (CompletionStage<?>) returnValue;
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
index e3dd91d2ad..b195f353a8 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpHeadersReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,7 +46,7 @@ public class HttpHeadersReturnValueHandler implements HandlerMethodReturnValueHa
 
 		mavContainer.setRequestHandled(true);
 
-		Assert.isInstanceOf(HttpHeaders.class, returnValue);
+		Assert.isInstanceOf(HttpHeaders.class, returnValue, "HttpHeaders expected");
 		HttpHeaders headers = (HttpHeaders) returnValue;
 
 		if (!headers.isEmpty()) {
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
index e9e302a533..cfc54188d8 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -240,7 +240,7 @@ public class MvcUriComponentsBuilder {
 	 * @return a UriComponents instance
 	 */
 	public static UriComponentsBuilder fromMethodCall(Object info) {
-		Assert.isInstanceOf(MethodInvocationInfo.class, info);
+		Assert.isInstanceOf(MethodInvocationInfo.class, info, "MethodInvocationInfo required");
 		MethodInvocationInfo invocationInfo = (MethodInvocationInfo) info;
 		Class<?> controllerType = invocationInfo.getControllerType();
 		Method method = invocationInfo.getControllerMethod();
@@ -260,7 +260,7 @@ public class MvcUriComponentsBuilder {
 	 * @return a UriComponents instance
 	 */
 	public static UriComponentsBuilder fromMethodCall(UriComponentsBuilder builder, Object info) {
-		Assert.isInstanceOf(MethodInvocationInfo.class, info);
+		Assert.isInstanceOf(MethodInvocationInfo.class, info, "MethodInvocationInfo required");
 		MethodInvocationInfo invocationInfo = (MethodInvocationInfo) info;
 		Class<?> controllerType = invocationInfo.getControllerType();
 		Method method = invocationInfo.getControllerMethod();
@@ -533,18 +533,13 @@ public class MvcUriComponentsBuilder {
 	private static WebApplicationContext getWebApplicationContext() {
 		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
 		if (requestAttributes == null) {
-			logger.debug("No request bound to the current thread: is DispatcherSerlvet used?");
+			logger.debug("No request bound to the current thread: not in a DispatcherServlet request?");
 			return null;
 		}
 
 		HttpServletRequest request = ((ServletRequestAttributes) requestAttributes).getRequest();
-		if (request == null) {
-			logger.debug("Request bound to current thread is not an HttpServletRequest");
-			return null;
-		}
-
-		String attributeName = DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE;
-		WebApplicationContext wac = (WebApplicationContext) request.getAttribute(attributeName);
+		WebApplicationContext wac = (WebApplicationContext)
+				request.getAttribute(DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE);
 		if (wac == null) {
 			logger.debug("No WebApplicationContext found: not in a DispatcherServlet request?");
 			return null;
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
index a48efb1b9e..0cc38d3613 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -396,7 +396,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * @param interceptors the interceptors to register
 	 */
 	public void setCallableInterceptors(List<CallableProcessingInterceptor> interceptors) {
-		Assert.notNull(interceptors);
+		Assert.notNull(interceptors, "CallableProcessingInterceptor List must not be null");
 		this.callableInterceptors = interceptors.toArray(new CallableProcessingInterceptor[interceptors.size()]);
 	}
 
@@ -405,7 +405,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * @param interceptors the interceptors to register
 	 */
 	public void setDeferredResultInterceptors(List<DeferredResultProcessingInterceptor> interceptors) {
-		Assert.notNull(interceptors);
+		Assert.notNull(interceptors, "DeferredResultProcessingInterceptor List must not be null");
 		this.deferredResultInterceptors = interceptors.toArray(new DeferredResultProcessingInterceptor[interceptors.size()]);
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
index 264ca73ce8..3224cfa689 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,9 +63,9 @@ public class ResponseBodyEmitterReturnValueHandler implements AsyncHandlerMethod
 
 
 	public ResponseBodyEmitterReturnValueHandler(List<HttpMessageConverter<?>> messageConverters) {
-		Assert.notEmpty(messageConverters, "'messageConverters' must not be empty");
+		Assert.notEmpty(messageConverters, "HttpMessageConverter List must not be empty");
 		this.messageConverters = messageConverters;
-		this.adapterMap = new HashMap<Class<?>, ResponseBodyEmitterAdapter>(3);
+		this.adapterMap = new HashMap<Class<?>, ResponseBodyEmitterAdapter>(4);
 		this.adapterMap.put(ResponseBodyEmitter.class, new SimpleResponseBodyEmitterAdapter());
 	}
 
@@ -146,7 +146,10 @@ public class ResponseBodyEmitterReturnValueHandler implements AsyncHandlerMethod
 		ShallowEtagHeaderFilter.disableContentCaching(request);
 
 		ResponseBodyEmitterAdapter adapter = getAdapterFor(returnValue.getClass());
-		Assert.notNull(adapter);
+		if (adapter == null) {
+			throw new IllegalStateException(
+					"Could not find ResponseBodyEmitterAdapter for return value type: " + returnValue.getClass());
+		}
 		ResponseBodyEmitter emitter = adapter.adaptToEmitter(returnValue, outputMessage);
 		emitter.extendResponse(outputMessage);
 
@@ -170,7 +173,7 @@ public class ResponseBodyEmitterReturnValueHandler implements AsyncHandlerMethod
 
 		@Override
 		public ResponseBodyEmitter adaptToEmitter(Object returnValue, ServerHttpResponse response) {
-			Assert.isInstanceOf(ResponseBodyEmitter.class, returnValue);
+			Assert.isInstanceOf(ResponseBodyEmitter.class, returnValue, "ResponseBodyEmitter expected");
 			return (ResponseBodyEmitter) returnValue;
 		}
 	}
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
index a3b646125c..cbbd1e62a9 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/StreamingResponseBodyReturnValueHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,7 +82,7 @@ public class StreamingResponseBodyReturnValueHandler implements HandlerMethodRet
 		ServletRequest request = webRequest.getNativeRequest(ServletRequest.class);
 		ShallowEtagHeaderFilter.disableContentCaching(request);
 
-		Assert.isInstanceOf(StreamingResponseBody.class, returnValue);
+		Assert.isInstanceOf(StreamingResponseBody.class, returnValue, "StreamingResponseBody expected");
 		StreamingResponseBody streamingBody = (StreamingResponseBody) returnValue;
 
 		Callable<Void> callable = new StreamingResponseBodyTask(outputMessage.getBody(), streamingBody);
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
index 367aed8503..f39c12a45b 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -186,12 +186,9 @@ public class ServletUriComponentsBuilder extends UriComponentsBuilder {
 	 * Obtain current request through {@link RequestContextHolder}.
 	 */
 	protected static HttpServletRequest getCurrentRequest() {
-		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
-		Assert.state(requestAttributes != null, "Could not find current request via RequestContextHolder");
-		Assert.isInstanceOf(ServletRequestAttributes.class, requestAttributes);
-		HttpServletRequest servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
-		Assert.state(servletRequest != null, "Could not find current HttpServletRequest");
-		return servletRequest;
+		RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
+		Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
+		return ((ServletRequestAttributes) attrs).getRequest();
 	}
 
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
index 7d1b432fcb..7b7067506f 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -214,7 +214,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	@Override
 	public View resolveViewName(String viewName, Locale locale) throws Exception {
 		RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
-		Assert.isInstanceOf(ServletRequestAttributes.class, attrs);
+		Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
 		List<MediaType> requestedMediaTypes = getMediaTypes(((ServletRequestAttributes) attrs).getRequest());
 		if (requestedMediaTypes != null) {
 			List<View> candidateViews = getCandidateViews(viewName, locale, requestedMediaTypes);
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
index 73f4fbed2b..6e2d84465b 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -121,7 +121,7 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 	 * See {@link ScriptTemplateConfigurer#setEngine(ScriptEngine)} documentation.
 	 */
 	public void setEngine(ScriptEngine engine) {
-		Assert.isInstanceOf(Invocable.class, engine);
+		Assert.isInstanceOf(Invocable.class, engine, "ScriptEngine must implement Invocable");
 		this.engine = engine;
 	}
 
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
index 44a22bb6ca..3709a5e8ed 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,14 +22,12 @@ import org.junit.Before;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
-import static org.mockito.Mockito.*;
-
 import org.mockito.MockitoAnnotations;
 
 import org.springframework.http.MediaType;
-import org.springframework.util.Assert;
 
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
 
 /**
  * Unit tests for {@link ResponseBodyEmitter}.
@@ -166,7 +164,7 @@ public class ResponseBodyEmitterTests {
 		verify(this.handler).onTimeout(captor.capture());
 		verify(this.handler).onCompletion(any());
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -182,7 +180,7 @@ public class ResponseBodyEmitterTests {
 		Runnable runnable = mock(Runnable.class);
 		this.emitter.onTimeout(runnable);
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -197,7 +195,7 @@ public class ResponseBodyEmitterTests {
 		verify(this.handler).onTimeout(any());
 		verify(this.handler).onCompletion(captor.capture());
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
@@ -213,7 +211,7 @@ public class ResponseBodyEmitterTests {
 		Runnable runnable = mock(Runnable.class);
 		this.emitter.onCompletion(runnable);
 
-		Assert.notNull(captor.getValue());
+		assertNotNull(captor.getValue());
 		captor.getValue().run();
 		verify(runnable).run();
 	}
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java b/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
index 58c4ef1f49..02b3f9f6dc 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/AbstractWebSocketHandlerRegistration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,8 +28,8 @@ import org.springframework.util.ObjectUtils;
 import org.springframework.web.socket.WebSocketHandler;
 import org.springframework.web.socket.server.HandshakeHandler;
 import org.springframework.web.socket.server.HandshakeInterceptor;
-import org.springframework.web.socket.server.support.OriginHandshakeInterceptor;
 import org.springframework.web.socket.server.support.DefaultHandshakeHandler;
+import org.springframework.web.socket.server.support.OriginHandshakeInterceptor;
 import org.springframework.web.socket.sockjs.SockJsService;
 import org.springframework.web.socket.sockjs.transport.handler.WebSocketTransportHandler;
 
@@ -45,7 +45,8 @@ public abstract class AbstractWebSocketHandlerRegistration<M> implements WebSock
 
 	private final TaskScheduler sockJsTaskScheduler;
 
-	private MultiValueMap<WebSocketHandler, String> handlerMap = new LinkedMultiValueMap<WebSocketHandler, String>();
+	private final MultiValueMap<WebSocketHandler, String> handlerMap =
+			new LinkedMultiValueMap<WebSocketHandler, String>();
 
 	private HandshakeHandler handshakeHandler;
 
@@ -63,8 +64,8 @@ public abstract class AbstractWebSocketHandlerRegistration<M> implements WebSock
 
 	@Override
 	public WebSocketHandlerRegistration addHandler(WebSocketHandler handler, String... paths) {
-		Assert.notNull(handler);
-		Assert.notEmpty(paths);
+		Assert.notNull(handler, "WebSocketHandler must not be null");
+		Assert.notEmpty(paths, "Paths must not be empty");
 		this.handlerMap.put(handler, Arrays.asList(paths));
 		return this;
 	}
@@ -108,13 +109,15 @@ public abstract class AbstractWebSocketHandlerRegistration<M> implements WebSock
 			this.sockJsServiceRegistration.setTransportHandlerOverrides(transportHandler);
 		}
 		if (!this.allowedOrigins.isEmpty()) {
-			this.sockJsServiceRegistration.setAllowedOrigins(this.allowedOrigins.toArray(new String[this.allowedOrigins.size()]));
+			this.sockJsServiceRegistration.setAllowedOrigins(
+					this.allowedOrigins.toArray(new String[this.allowedOrigins.size()]));
 		}
 		return this.sockJsServiceRegistration;
 	}
 
 	protected HandshakeInterceptor[] getInterceptors() {
-		List<HandshakeInterceptor> interceptors = new ArrayList<HandshakeInterceptor>();
+		List<HandshakeInterceptor> interceptors =
+				new ArrayList<HandshakeInterceptor>(this.interceptors.size() + 1);
 		interceptors.addAll(this.interceptors);
 		interceptors.add(new OriginHandshakeInterceptor(this.allowedOrigins));
 		return interceptors.toArray(new HandshakeInterceptor[interceptors.size()]);
@@ -126,7 +129,7 @@ public abstract class AbstractWebSocketHandlerRegistration<M> implements WebSock
 			SockJsService sockJsService = this.sockJsServiceRegistration.getSockJsService();
 			for (WebSocketHandler wsHandler : this.handlerMap.keySet()) {
 				for (String path : this.handlerMap.get(wsHandler)) {
-					String pathPattern = path.endsWith("/") ? path + "**" : path + "/**";
+					String pathPattern = (path.endsWith("/") ? path + "**" : path + "/**");
 					addSockJsServiceMapping(mappings, sockJsService, wsHandler, pathPattern);
 				}
 			}
@@ -145,9 +148,10 @@ public abstract class AbstractWebSocketHandlerRegistration<M> implements WebSock
 	}
 
 	private HandshakeHandler getOrCreateHandshakeHandler() {
-		return (this.handshakeHandler != null) ? this.handshakeHandler : new DefaultHandshakeHandler();
+		return (this.handshakeHandler != null ? this.handshakeHandler : new DefaultHandshakeHandler());
 	}
 
+
 	protected abstract M createMappings();
 
 	protected abstract void addSockJsServiceMapping(M mappings, SockJsService sockJsService,
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java b/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
index 90a1aac47d..11a03ec00d 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -60,6 +60,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		return Ordered.LOWEST_PRECEDENCE;
 	}
 
+
 	// SmartApplicationListener methods
 
 	@Override
@@ -69,7 +70,6 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 	@Override
 	public void onApplicationEvent(ApplicationEvent event) {
-
 		AbstractSubProtocolEvent subProtocolEvent = (AbstractSubProtocolEvent) event;
 		Message<?> message = subProtocolEvent.getMessage();
 		SimpMessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, SimpMessageHeaderAccessor.class);
@@ -129,6 +129,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		return true;
 	}
 
+
 	// SimpUserRegistry methods
 
 	@Override
@@ -169,12 +170,10 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final String name;
 
-		private final Map<String, SimpSession> userSessions =
-				new ConcurrentHashMap<String, SimpSession>(1);
-
+		private final Map<String, SimpSession> userSessions = new ConcurrentHashMap<String, SimpSession>(1);
 
 		public LocalSimpUser(String userName) {
-			Assert.notNull(userName);
+			Assert.notNull(userName, "User name must not be null");
 			this.name = userName;
 		}
 
@@ -208,13 +207,8 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		@Override
 		public boolean equals(Object other) {
-			if (this == other) {
-				return true;
-			}
-			if (other == null || !(other instanceof SimpUser)) {
-				return false;
-			}
-			return this.name.equals(((SimpUser) other).getName());
+			return (this == other ||
+					(other instanceof SimpUser && this.name.equals(((SimpUser) other).getName())));
 		}
 
 		@Override
@@ -228,6 +222,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 	}
 
+
 	private static class LocalSimpSession implements SimpSession {
 
 		private final String id;
@@ -236,10 +231,9 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final Map<String, SimpSubscription> subscriptions = new ConcurrentHashMap<String, SimpSubscription>(4);
 
-
 		public LocalSimpSession(String id, LocalSimpUser user) {
-			Assert.notNull(id);
-			Assert.notNull(user);
+			Assert.notNull(id, "Id must not be null");
+			Assert.notNull(user, "User must not be null");
 			this.id = id;
 			this.user = user;
 		}
@@ -268,19 +262,14 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 
 		@Override
-		public int hashCode() {
-			return this.id.hashCode();
+		public boolean equals(Object other) {
+			return (this == other ||
+					(other instanceof SimpSubscription && this.id.equals(((SimpSubscription) other).getId())));
 		}
 
 		@Override
-		public boolean equals(Object other) {
-			if (this == other) {
-				return true;
-			}
-			if (other == null || !(other instanceof SimpSubscription)) {
-				return false;
-			}
-			return this.id.equals(((SimpSubscription) other).getId());
+		public int hashCode() {
+			return this.id.hashCode();
 		}
 
 		@Override
@@ -289,6 +278,7 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		}
 	}
 
+
 	private static class LocalSimpSubscription implements SimpSubscription {
 
 		private final String id;
@@ -297,11 +287,10 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 
 		private final String destination;
 
-
 		public LocalSimpSubscription(String id, String destination, LocalSimpSession session) {
-			Assert.notNull(id);
-			Assert.hasText(destination);
-			Assert.notNull(session);
+			Assert.notNull(id, "Id must not be null");
+			Assert.hasText(destination, "Destination must not be empty");
+			Assert.notNull(session, "Session must not be null");
 			this.id = id;
 			this.destination = destination;
 			this.session = session;
@@ -322,22 +311,22 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 			return this.destination;
 		}
 
-		@Override
-		public int hashCode() {
-			return 31 * this.id.hashCode() + getSession().hashCode();
-		}
-
 		@Override
 		public boolean equals(Object other) {
 			if (this == other) {
 				return true;
 			}
-			if (other == null || !(other instanceof SimpSubscription)) {
+			if (!(other instanceof SimpSubscription)) {
 				return false;
 			}
 			SimpSubscription otherSubscription = (SimpSubscription) other;
-			return (getSession().getId().equals(otherSubscription.getSession().getId()) &&
-					this.id.equals(otherSubscription.getId()));
+			return (this.id.equals(otherSubscription.getId()) &&
+					getSession().getId().equals(otherSubscription.getSession().getId()));
+		}
+
+		@Override
+		public int hashCode() {
+			return this.id.hashCode() * 31 + getSession().getId().hashCode();
 		}
 
 		@Override
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
index ce6a3085cf..34147e3893 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -174,10 +174,10 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 			String selectedProtocol, List<WebSocketExtension> selectedExtensions, Principal user,
 			WebSocketHandler wsHandler, Map<String, Object> attributes) throws HandshakeFailureException {
 
-		Assert.isInstanceOf(ServletServerHttpRequest.class, request);
+		Assert.isInstanceOf(ServletServerHttpRequest.class, request, "ServletServerHttpRequest required");
 		HttpServletRequest servletRequest = ((ServletServerHttpRequest) request).getServletRequest();
 
-		Assert.isInstanceOf(ServletServerHttpResponse.class, response);
+		Assert.isInstanceOf(ServletServerHttpResponse.class, response, "ServletServerHttpResponse required");
 		HttpServletResponse servletResponse = ((ServletServerHttpResponse) response).getServletResponse();
 
 		Assert.isTrue(this.factoryAdapter.getFactory().isUpgradeRequest(servletRequest, servletResponse),
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java b/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
index 2dd7ff41ac..246f0900be 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/server/standard/AbstractStandardUpgradeStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,12 +71,12 @@ public abstract class AbstractStandardUpgradeStrategy implements RequestUpgradeS
 	}
 
 	protected final HttpServletRequest getHttpServletRequest(ServerHttpRequest request) {
-		Assert.isTrue(request instanceof ServletServerHttpRequest);
+		Assert.isInstanceOf(ServletServerHttpRequest.class, request, "ServletServerHttpRequest required");
 		return ((ServletServerHttpRequest) request).getServletRequest();
 	}
 
 	protected final HttpServletResponse getHttpServletResponse(ServerHttpResponse response) {
-		Assert.isTrue(response instanceof ServletServerHttpResponse);
+		Assert.isInstanceOf(ServletServerHttpResponse.class, response, "ServletServerHttpResponse required");
 		return ((ServletServerHttpResponse) response).getServletResponse();
 	}
 
@@ -92,8 +92,8 @@ public abstract class AbstractStandardUpgradeStrategy implements RequestUpgradeS
 
 	protected List<WebSocketExtension> getInstalledExtensions(WebSocketContainer container) {
 		List<WebSocketExtension> result = new ArrayList<WebSocketExtension>();
-		for (Extension ext : container.getInstalledExtensions()) {
-			result.add(new StandardToWebSocketExtensionAdapter(ext));
+		for (Extension extension : container.getInstalledExtensions()) {
+			result.add(new StandardToWebSocketExtensionAdapter(extension));
 		}
 		return result;
 	}
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
index cab4e6cf48..3b48a7706d 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/RestTemplateXhrTransport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -81,7 +81,7 @@ public class RestTemplateXhrTransport extends AbstractXhrTransport {
 	 * time the transports connects.
 	 */
 	public void setTaskExecutor(TaskExecutor taskExecutor) {
-		Assert.notNull(this.taskExecutor);
+		Assert.notNull(taskExecutor, "TaskExecutor must not be null");
 		this.taskExecutor = taskExecutor;
 	}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
index 1a7dc43f3c..e5c4a10ef3 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.springframework.web.socket.sockjs.client;
 import java.net.URI;
 import java.util.Collections;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -82,7 +82,7 @@ public class WebSocketTransport implements Transport, Lifecycle {
 		URI url = request.getTransportUrl();
 		WebSocketHttpHeaders headers = new WebSocketHttpHeaders(request.getHandshakeHeaders());
 		if (logger.isDebugEnabled()) {
-			logger.debug("Starting WebSocket session url=" + url);
+			logger.debug("Starting WebSocket session on " + url);
 		}
 		this.webSocketClient.doHandshake(handler, headers, url).addCallback(
 				new ListenableFutureCallback<WebSocketSession>() {
@@ -144,16 +144,16 @@ public class WebSocketTransport implements Transport, Lifecycle {
 
 		private final WebSocketClientSockJsSession sockJsSession;
 
-		private final AtomicInteger connectCount = new AtomicInteger(0);
+		private final AtomicBoolean connected = new AtomicBoolean(false);
 
 		public ClientSockJsWebSocketHandler(WebSocketClientSockJsSession session) {
-			Assert.notNull(session);
+			Assert.notNull(session, "Session must not be null");
 			this.sockJsSession = session;
 		}
 
 		@Override
 		public void afterConnectionEstablished(WebSocketSession webSocketSession) throws Exception {
-			Assert.isTrue(this.connectCount.compareAndSet(0, 1));
+			Assert.state(this.connected.compareAndSet(false, true), "Already connected");
 			this.sockJsSession.initializeDelegateSession(webSocketSession);
 		}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
index 5905bf5819..c9f170d598 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractSockJsSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -162,7 +162,7 @@ public abstract class AbstractSockJsSession implements SockJsSession {
 
 	public final void sendMessage(WebSocketMessage<?> message) throws IOException {
 		Assert.state(!isClosed(), "Cannot send a message when session is closed");
-		Assert.isInstanceOf(TextMessage.class, message, "SockJS supports text messages only: " + message);
+		Assert.isInstanceOf(TextMessage.class, message, "SockJS supports text messages only");
 		sendMessageInternal(((TextMessage) message).getPayload());
 	}
 
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
index 4dec50eee4..4d89acbdba 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -67,7 +67,7 @@ public abstract class StreamingSockJsSession extends AbstractHttpSockJsSession {
 			boolean initialRequest) throws IOException {
 
 		byte[] prelude = getPrelude(request);
-		Assert.notNull(prelude);
+		Assert.state(prelude != null, "Prelude expected");
 		response.getBody().write(prelude);
 		response.flush();