Polish Collection.toArray

Consistently use `StringUtils.toStringArray`, `ClassUtils.toClassArray`
or zero length when converting collections to arrays.

Fixes gh-12160

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/server/ManagementContextConfigurationImportSelector.java

@@ -32,6 +32,7 @@ import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.SimpleMetadataReaderFactory;
+import org.springframework.util.StringUtils;
 
 /**
  * Selects configuration classes for the management context configuration. Entries are
@@ -65,7 +66,7 @@ class ManagementContextConfigurationImportSelector
 				names.add(configuration.getClassName());
 			}
 		}
-		return names.toArray(new String[names.size()]);
+		return StringUtils.toStringArray(names);
 	}
 
 	private List<ManagementConfiguration> getConfigurations() {

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/servlet/ServletManagementContextFactory.java

@@ -32,6 +32,7 @@ import org.springframework.boot.web.context.ConfigurableWebServerApplicationCont
 import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
 import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
 import org.springframework.context.ApplicationContext;
+import org.springframework.util.ClassUtils;
 
 /**
  * A {@link ManagementContextFactory} for servlet-based web applications.
@@ -47,7 +48,7 @@ class ServletManagementContextFactory implements ManagementContextFactory {
 		child.setParent(parent);
 		List<Class<?>> combinedClasses = new ArrayList<>(Arrays.asList(configClasses));
 		combinedClasses.add(ServletWebServerFactoryAutoConfiguration.class);
-		child.register(combinedClasses.toArray(new Class<?>[combinedClasses.size()]));
+		child.register(ClassUtils.toClassArray(combinedClasses));
 		registerServletWebServerFactory(parent, child);
 		return child;
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/integrationtest/EndpointAutoConfigurationClasses.java

@@ -30,6 +30,7 @@ import org.springframework.boot.actuate.autoconfigure.info.InfoEndpointAutoConfi
 import org.springframework.boot.actuate.autoconfigure.management.ThreadDumpEndpointAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.trace.http.HttpTraceEndpointAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.web.mappings.MappingsEndpointAutoConfiguration;
+import org.springframework.util.ClassUtils;
 
 /**
  * A list of all endpoint auto-configuration classes for use in tests.
@@ -51,7 +52,7 @@ final class EndpointAutoConfigurationClasses {
 		all.add(ThreadDumpEndpointAutoConfiguration.class);
 		all.add(HttpTraceEndpointAutoConfiguration.class);
 		all.add(MappingsEndpointAutoConfiguration.class);
-		ALL = all.toArray(new Class<?>[] {});
+		ALL = ClassUtils.toClassArray(all);
 	}
 
 	private EndpointAutoConfigurationClasses() {

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/elasticsearch/ElasticsearchHealthIndicator.java

@@ -27,6 +27,7 @@ import org.springframework.boot.actuate.health.AbstractHealthIndicator;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.HealthIndicator;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link HealthIndicator} for an Elasticsearch cluster.
@@ -53,8 +54,8 @@ public class ElasticsearchHealthIndicator extends AbstractHealthIndicator {
 	 */
 	public ElasticsearchHealthIndicator(Client client, long responseTimeout,
 			List<String> indices) {
-		this(client, responseTimeout, (indices == null ? null
-				: indices.toArray(new String[indices.size()])));
+		this(client, responseTimeout,
+				(indices == null ? null : StringUtils.toStringArray(indices)));
 	}
 
 	/**

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/web/jersey/JerseyEndpointResourceFactory.java

@@ -94,23 +94,18 @@ public class JerseyEndpointResourceFactory {
 		Builder resourceBuilder = Resource.builder()
 				.path(endpointMapping.createSubPath(requestPredicate.getPath()));
 		resourceBuilder.addMethod(requestPredicate.getHttpMethod().name())
-				.consumes(toStringArray(requestPredicate.getConsumes()))
-				.produces(toStringArray(requestPredicate.getProduces()))
+				.consumes(StringUtils.toStringArray(requestPredicate.getConsumes()))
+				.produces(StringUtils.toStringArray(requestPredicate.getProduces()))
 				.handledBy(new OperationInflector(operation,
 						!requestPredicate.getConsumes().isEmpty()));
 		return resourceBuilder.build();
 	}
 
-	private String[] toStringArray(Collection<String> collection) {
-		return collection.toArray(new String[collection.size()]);
-	}
-
 	private Resource createEndpointLinksResource(String endpointPath,
 			EndpointMediaTypes endpointMediaTypes, EndpointLinksResolver linksResolver) {
 		Builder resourceBuilder = Resource.builder().path(endpointPath);
 		resourceBuilder.addMethod("GET")
-				.produces(endpointMediaTypes.getProduced()
-						.toArray(new String[endpointMediaTypes.getProduced().size()]))
+				.produces(StringUtils.toStringArray(endpointMediaTypes.getProduced()))
 				.handledBy(new EndpointLinksInflector(linksResolver));
 		return resourceBuilder.build();
 	}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/web/reactive/AbstractWebFluxEndpointHandlerMapping.java

@@ -167,25 +167,20 @@ public abstract class AbstractWebFluxEndpointHandlerMapping
 		RequestMethodsRequestCondition methods = new RequestMethodsRequestCondition(
 				RequestMethod.valueOf(predicate.getHttpMethod().name()));
 		ConsumesRequestCondition consumes = new ConsumesRequestCondition(
-				toStringArray(predicate.getConsumes()));
+				StringUtils.toStringArray(predicate.getConsumes()));
 		ProducesRequestCondition produces = new ProducesRequestCondition(
-				toStringArray(predicate.getProduces()));
+				StringUtils.toStringArray(predicate.getProduces()));
 		return new RequestMappingInfo(null, patterns, methods, null, null, consumes,
 				produces, null);
 	}
 
-	private String[] toStringArray(Collection<String> collection) {
-		return collection.toArray(new String[collection.size()]);
-	}
-
 	private void registerLinksMapping() {
 		PatternsRequestCondition patterns = new PatternsRequestCondition(
 				pathPatternParser.parse(this.endpointMapping.getPath()));
 		RequestMethodsRequestCondition methods = new RequestMethodsRequestCondition(
 				RequestMethod.GET);
 		ProducesRequestCondition produces = new ProducesRequestCondition(
-				this.endpointMediaTypes.getProduced().toArray(
-						new String[this.endpointMediaTypes.getProduced().size()]));
+				StringUtils.toStringArray(this.endpointMediaTypes.getProduced()));
 		RequestMappingInfo mapping = new RequestMappingInfo(patterns, methods, null, null,
 				null, produces, null);
 		registerMapping(mapping, this, this.linksMethod);

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/web/servlet/AbstractWebMvcEndpointHandlerMapping.java

@@ -155,24 +155,20 @@ public abstract class AbstractWebMvcEndpointHandlerMapping
 		RequestMethodsRequestCondition methods = new RequestMethodsRequestCondition(
 				RequestMethod.valueOf(predicate.getHttpMethod().name()));
 		ConsumesRequestCondition consumes = new ConsumesRequestCondition(
-				toStringArray(predicate.getConsumes()));
+				StringUtils.toStringArray(predicate.getConsumes()));
 		ProducesRequestCondition produces = new ProducesRequestCondition(
-				toStringArray(predicate.getProduces()));
+				StringUtils.toStringArray(predicate.getProduces()));
 		return new RequestMappingInfo(null, patterns, methods, null, null, consumes,
 				produces, null);
 	}
 
-	private String[] toStringArray(Collection<String> collection) {
-		return collection.toArray(new String[collection.size()]);
-	}
-
 	private void registerLinksMapping() {
 		PatternsRequestCondition patterns = patternsRequestConditionForPattern("");
 		RequestMethodsRequestCondition methods = new RequestMethodsRequestCondition(
 				RequestMethod.GET);
 		ProducesRequestCondition produces = new ProducesRequestCondition(
-				this.endpointMediaTypes.getProduced().toArray(
-						new String[this.endpointMediaTypes.getProduced().size()]));
+				this.endpointMediaTypes.getProduced().toArray(StringUtils
+						.toStringArray(this.endpointMediaTypes.getProduced())));
 		RequestMappingInfo mapping = new RequestMappingInfo(patterns, methods, null, null,
 				null, produces, null);
 		registerMapping(mapping, this, this.linksMethod);

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpointTests.java

@@ -35,6 +35,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -177,8 +178,7 @@ public class ConfigurationPropertiesReportEndpointTests {
 			ConfigurationPropertiesReportEndpoint endpoint = context
 					.getBean(ConfigurationPropertiesReportEndpoint.class);
 			if (!CollectionUtils.isEmpty(keysToSanitize)) {
-				endpoint.setKeysToSanitize(
-						keysToSanitize.toArray(new String[keysToSanitize.size()]));
+				endpoint.setKeysToSanitize(StringUtils.toStringArray(keysToSanitize));
 			}
 			properties.accept(context, endpoint.configurationProperties().getContexts()
 					.get(context.getId()));

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/annotation/EndpointDiscovererTests.java

@@ -264,7 +264,7 @@ public class EndpointDiscovererTests {
 		methods.add(findTestEndpointMethod("getOne", String.class));
 		methods.add(findTestEndpointMethod("update", String.class, String.class));
 		methods.add(findTestEndpointMethod("deleteOne", String.class));
-		return methods.toArray(new Method[] {});
+		return methods.toArray(new Method[0]);
 	}
 
 	private Method findTestEndpointMethod(String name, Class<?>... paramTypes) {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/test/JerseyEndpointsRunner.java

@@ -47,6 +47,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.util.ClassUtils;
 
 /**
  * {@link BlockJUnit4ClassRunner} for Jersey.
@@ -63,7 +64,7 @@ class JerseyEndpointsRunner extends AbstractWebEndpointRunner {
 	private static ConfigurableApplicationContext createContext(List<Class<?>> classes) {
 		AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();
 		classes.add(JerseyEndpointConfiguration.class);
-		context.register(classes.toArray(new Class<?>[classes.size()]));
+		context.register(ClassUtils.toClassArray(classes));
 		context.refresh();
 		return context;
 	}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/test/WebFluxEndpointsRunner.java

@@ -44,6 +44,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.MediaType;
 import org.springframework.http.server.reactive.HttpHandler;
+import org.springframework.util.ClassUtils;
 import org.springframework.web.cors.CorsConfiguration;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
 
@@ -62,7 +63,7 @@ class WebFluxEndpointsRunner extends AbstractWebEndpointRunner {
 	private static ConfigurableApplicationContext createContext(List<Class<?>> classes) {
 		AnnotationConfigReactiveWebServerApplicationContext context = new AnnotationConfigReactiveWebServerApplicationContext();
 		classes.add(WebFluxEndpointConfiguration.class);
-		context.register(classes.toArray(new Class<?>[classes.size()]));
+		context.register(ClassUtils.toClassArray(classes));
 		context.refresh();
 		return context;
 	}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/test/WebMvcEndpointRunner.java

@@ -43,6 +43,7 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.MediaType;
+import org.springframework.util.ClassUtils;
 import org.springframework.web.cors.CorsConfiguration;
 
 /**
@@ -60,7 +61,7 @@ class WebMvcEndpointRunner extends AbstractWebEndpointRunner {
 	private static ConfigurableApplicationContext createContext(List<Class<?>> classes) {
 		AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();
 		classes.add(WebMvcEndpointConfiguration.class);
-		context.register(classes.toArray(new Class<?>[classes.size()]));
+		context.register(ClassUtils.toClassArray(classes));
 		context.refresh();
 		return context;
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurationImportSelector.java

@@ -50,6 +50,7 @@ import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link DeferredImportSelector} to handle {@link EnableAutoConfiguration
@@ -100,7 +101,7 @@ public class AutoConfigurationImportSelector
 			configurations.removeAll(exclusions);
 			configurations = filter(configurations, autoConfigurationMetadata);
 			fireAutoConfigurationImportEvents(configurations, exclusions);
-			return configurations.toArray(new String[configurations.size()]);
+			return StringUtils.toStringArray(configurations);
 		}
 		catch (IOException ex) {
 			throw new IllegalStateException(ex);
@@ -235,7 +236,7 @@ public class AutoConfigurationImportSelector
 	private List<String> filter(List<String> configurations,
 			AutoConfigurationMetadata autoConfigurationMetadata) {
 		long startTime = System.nanoTime();
-		String[] candidates = configurations.toArray(new String[configurations.size()]);
+		String[] candidates = StringUtils.toStringArray(configurations);
 		boolean[] skip = new boolean[candidates.length];
 		boolean skipped = false;
 		for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurationPackages.java

@@ -114,7 +114,7 @@ public abstract class AutoConfigurationPackages {
 		Set<String> merged = new LinkedHashSet<>();
 		merged.addAll(Arrays.asList(existing));
 		merged.addAll(Arrays.asList(packageNames));
-		return merged.toArray(new String[merged.size()]);
+		return StringUtils.toStringArray(merged);
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cache/CouchbaseCacheConfiguration.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -32,6 +32,7 @@ import org.springframework.cache.CacheManager;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.util.StringUtils;
 
 /**
  * Couchbase cache configuration.
@@ -66,7 +67,7 @@ public class CouchbaseCacheConfiguration {
 		Couchbase couchbase = this.cacheProperties.getCouchbase();
 		PropertyMapper.get().from(couchbase::getExpiration).whenNonNull()
 				.asInt(Duration::getSeconds).to(builder::withExpiration);
-		String[] names = cacheNames.toArray(new String[cacheNames.size()]);
+		String[] names = StringUtils.toStringArray(cacheNames);
 		CouchbaseCacheManager cacheManager = new CouchbaseCacheManager(builder, names);
 		return this.customizers.customize(cacheManager);
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -33,6 +33,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Cassandra.
@@ -80,7 +81,7 @@ public class CassandraAutoConfiguration {
 		map.from(properties::isSsl).whenTrue().toCall(builder::withSSL);
 		map.from(this::getPoolingOptions).to(builder::withPoolingOptions);
 		map.from(properties::getContactPoints)
-				.as((list) -> list.toArray(new String[list.size()]))
+				.as((list) -> StringUtils.toStringArray(list))
 				.to(builder::addContactPoints);
 		customize(builder);
 		return builder.build();

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/neo4j/Neo4jDataAutoConfiguration.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -40,6 +40,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.data.neo4j.transaction.Neo4jTransactionManager;
 import org.springframework.data.neo4j.web.support.OpenSessionInViewInterceptor;
 import org.springframework.transaction.PlatformTransactionManager;
+import org.springframework.util.StringUtils;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
@@ -106,7 +107,7 @@ public class Neo4jDataAutoConfiguration {
 		if (packages.isEmpty() && AutoConfigurationPackages.has(applicationContext)) {
 			packages = AutoConfigurationPackages.get(applicationContext);
 		}
-		return packages.toArray(new String[packages.size()]);
+		return StringUtils.toStringArray(packages);
 	}
 
 	@Configuration

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/domain/EntityScanPackages.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -120,7 +120,7 @@ public class EntityScanPackages {
 			GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
 			beanDefinition.setBeanClass(EntityScanPackages.class);
 			beanDefinition.getConstructorArgumentValues().addIndexedArgumentValue(0,
-					packageNames.toArray(new String[packageNames.size()]));
+					StringUtils.toStringArray(packageNames));
 			beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 			registry.registerBeanDefinition(BEAN, beanDefinition);
 		}
@@ -134,7 +134,7 @@ public class EntityScanPackages {
 		Set<String> merged = new LinkedHashSet<>();
 		merged.addAll(Arrays.asList(existing));
 		merged.addAll(packageNames);
-		return merged.toArray(new String[merged.size()]);
+		return StringUtils.toStringArray(merged);
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfiguration.java

@@ -57,6 +57,7 @@ import org.springframework.orm.jpa.AbstractEntityManagerFactoryBean;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Flyway database migrations.
@@ -137,7 +138,7 @@ public class FlywayAutoConfiguration {
 				String password = getProperty(this.properties::getPassword,
 						this.dataSourceProperties::getPassword);
 				flyway.setDataSource(url, user, password,
-						this.properties.getInitSqls().toArray(new String[0]));
+						StringUtils.toStringArray(this.properties.getInitSqls()));
 			}
 			else if (this.flywayDataSource != null) {
 				flyway.setDataSource(this.flywayDataSource);
@@ -145,8 +146,7 @@ public class FlywayAutoConfiguration {
 			else {
 				flyway.setDataSource(this.dataSource);
 			}
-			flyway.setCallbacks(this.flywayCallbacks
-					.toArray(new FlywayCallback[this.flywayCallbacks.size()]));
+			flyway.setCallbacks(this.flywayCallbacks.toArray(new FlywayCallback[0]));
 			String[] locations = new LocationResolver(flyway.getDataSource())
 					.resolveLocations(this.properties.getLocations());
 			checkLocationExists(locations);
@@ -241,7 +241,7 @@ public class FlywayAutoConfiguration {
 		}
 
 		public String[] resolveLocations(Collection<String> locations) {
-			return resolveLocations(locations.toArray(new String[locations.size()]));
+			return resolveLocations(StringUtils.toStringArray(locations));
 		}
 
 		public String[] resolveLocations(String[] locations) {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfiguration.java

@@ -337,8 +337,7 @@ public class JacksonAutoConfiguration {
 			private void configureModules(Jackson2ObjectMapperBuilder builder) {
 				Collection<Module> moduleBeans = getBeans(this.applicationContext,
 						Module.class);
-				builder.modulesToInstall(
-						moduleBeans.toArray(new Module[moduleBeans.size()]));
+				builder.modulesToInstall(moduleBeans.toArray(new Module[0]));
 			}
 
 			private void configureLocale(Jackson2ObjectMapperBuilder builder) {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ldap/embedded/EmbeddedLdapAutoConfiguration.java

@@ -113,7 +113,7 @@ public class EmbeddedLdapAutoConfiguration {
 
 	@Bean
 	public InMemoryDirectoryServer directoryServer() throws LDAPException {
-		String[] baseDn = this.embeddedProperties.getBaseDn().toArray(new String[0]);
+		String[] baseDn = StringUtils.toStringArray(this.embeddedProperties.getBaseDn());
 		InMemoryDirectoryServerConfig config = new InMemoryDirectoryServerConfig(baseDn);
 		if (hasCredentials(this.embeddedProperties.getCredential())) {
 			config.addAdditionalBindCredentials(

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java

@@ -55,6 +55,7 @@ import org.springframework.orm.jpa.vendor.AbstractJpaVendorAdapter;
 import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.jta.JtaTransactionManager;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
@@ -160,13 +161,13 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware {
 		if (packages.isEmpty() && AutoConfigurationPackages.has(this.beanFactory)) {
 			packages = AutoConfigurationPackages.get(this.beanFactory);
 		}
-		return packages.toArray(new String[packages.size()]);
+		return StringUtils.toStringArray(packages);
 	}
 
 	private String[] getMappingResources() {
 		List<String> mappingResources = this.properties.getMappingResources();
 		return (!ObjectUtils.isEmpty(mappingResources)
-				? mappingResources.toArray(new String[mappingResources.size()]) : null);
+				? StringUtils.toStringArray(mappingResources) : null);
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesRegistrationAdapter.java

@@ -29,6 +29,7 @@ import org.springframework.security.oauth2.client.registration.ClientRegistratio
 import org.springframework.security.oauth2.client.registration.ClientRegistration.Builder;
 import org.springframework.security.oauth2.core.AuthorizationGrantType;
 import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+import org.springframework.util.StringUtils;
 
 /**
  * Adapter class to convert {@link OAuth2ClientProperties} to a
@@ -63,8 +64,7 @@ final class OAuth2ClientPropertiesRegistrationAdapter {
 		map.from(properties::getAuthorizationGrantType).as(AuthorizationGrantType::new)
 				.to(builder::authorizationGrantType);
 		map.from(properties::getRedirectUriTemplate).to(builder::redirectUriTemplate);
-		map.from(properties::getScope)
-				.as((scope) -> scope.toArray(new String[scope.size()]))
+		map.from(properties::getScope).as((scope) -> StringUtils.toStringArray(scope))
 				.to(builder::scope);
 		map.from(properties::getClientName).to(builder::clientName);
 		return builder.build();

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/reactive/ReactiveUserDetailsServiceAutoConfiguration.java

@@ -35,6 +35,7 @@ import org.springframework.security.core.userdetails.ReactiveUserDetailsService;
 import org.springframework.security.core.userdetails.User;
 import org.springframework.security.core.userdetails.UserDetails;
 import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.util.StringUtils;
 
 /**
  * Default user {@link Configuration} for a reactive web application. Configures a
@@ -72,7 +73,7 @@ public class ReactiveUserDetailsServiceAutoConfiguration {
 	private UserDetails getUserDetails(SecurityProperties.User user, String password) {
 		List<String> roles = user.getRoles();
 		return User.withUsername(user.getName()).password(password)
-				.roles(roles.toArray(new String[roles.size()])).build();
+				.roles(StringUtils.toStringArray(roles)).build();
 	}
 
 	private String getOrDeducePassword(SecurityProperties.User user,

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/servlet/UserDetailsServiceAutoConfiguration.java

@@ -36,6 +36,7 @@ import org.springframework.security.core.userdetails.User;
 import org.springframework.security.core.userdetails.UserDetailsService;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.security.provisioning.InMemoryUserDetailsManager;
+import org.springframework.util.StringUtils;
 
 /**
  * Configuration for a Spring Security in-memory {@link AuthenticationManager}. Adds an
@@ -71,7 +72,7 @@ public class UserDetailsServiceAutoConfiguration {
 		List<String> roles = user.getRoles();
 		return new InMemoryUserDetailsManager(User.withUsername(user.getName())
 				.password(getOrDeducePassword(user, passwordEncoder.getIfAvailable()))
-				.roles(roles.toArray(new String[roles.size()])).build());
+				.roles(StringUtils.toStringArray(roles)).build());
 	}
 
 	public String getOrDeducePassword(SecurityProperties.User user,

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/SessionAutoConfiguration.java

@@ -48,6 +48,7 @@ import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.session.ReactiveSessionRepository;
 import org.springframework.session.Session;
 import org.springframework.session.SessionRepository;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Spring Session.
@@ -113,7 +114,7 @@ public class SessionAutoConfiguration {
 				imports.add(SessionStoreMappings.getConfigurationClass(webApplicationType,
 						types[i]));
 			}
-			return imports.toArray(new String[imports.size()]);
+			return StringUtils.toStringArray(imports);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/couchbase/CouchbaseReactiveAndImperativeRepositoriesAutoConfigurationTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -36,6 +36,7 @@ import org.springframework.context.annotation.ImportSelector;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.data.couchbase.repository.config.EnableCouchbaseRepositories;
 import org.springframework.data.couchbase.repository.config.EnableReactiveCouchbaseRepositories;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -92,7 +93,7 @@ public class CouchbaseReactiveAndImperativeRepositoriesAutoConfigurationTests {
 					CouchbaseReactiveRepositoriesAutoConfiguration.class }) {
 				names.add(type.getName());
 			}
-			return names.toArray(new String[0]);
+			return StringUtils.toStringArray(names);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/mongo/MixedMongoRepositoriesAutoConfigurationTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.context.annotation.ImportSelector;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -164,7 +165,7 @@ public class MixedMongoRepositoriesAutoConfigurationTests {
 					MongoRepositoriesAutoConfiguration.class }) {
 				names.add(type.getName());
 			}
-			return names.toArray(new String[0]);
+			return StringUtils.toStringArray(names);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/mongo/MongoReactiveAndBlockingRepositoriesAutoConfigurationTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -36,6 +36,7 @@ import org.springframework.context.annotation.ImportSelector;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
 import org.springframework.data.mongodb.repository.config.EnableReactiveMongoRepositories;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -93,7 +94,7 @@ public class MongoReactiveAndBlockingRepositoriesAutoConfigurationTests {
 					MongoReactiveRepositoriesAutoConfiguration.class }) {
 				names.add(type.getName());
 			}
-			return names.toArray(new String[0]);
+			return StringUtils.toStringArray(names);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfigurationTests.java

@@ -47,6 +47,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.datasource.SimpleDriverDataSource;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -226,7 +227,7 @@ public class DataSourceAutoConfigurationTests {
 	private <T extends DataSource> void assertDataSource(Class<T> expectedType,
 			List<String> hiddenPackages, Consumer<T> consumer) {
 		FilteredClassLoader classLoader = new FilteredClassLoader(
-				hiddenPackages.toArray(new String[hiddenPackages.size()]));
+				StringUtils.toStringArray(hiddenPackages));
 		this.contextRunner.withClassLoader(classLoader).run((context) -> {
 			DataSource bean = context.getBean(DataSource.class);
 			assertThat(bean).isInstanceOf(expectedType);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jms/activemq/ActiveMQAutoConfigurationTests.java

@@ -27,6 +27,7 @@ import org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -89,8 +90,9 @@ public class ActiveMQAutoConfigurationTests {
 							.isEqualTo(defaultFactory.getSendTimeout());
 					assertThat(connectionFactory.isTrustAllPackages())
 							.isEqualTo(defaultFactory.isTrustAllPackages());
-					assertThat(connectionFactory.getTrustedPackages()).containsExactly(
-							defaultFactory.getTrustedPackages().toArray(new String[] {}));
+					assertThat(connectionFactory.getTrustedPackages())
+							.containsExactly(StringUtils
+									.toStringArray(defaultFactory.getTrustedPackages()));
 				});
 	}
 
@@ -113,8 +115,7 @@ public class ActiveMQAutoConfigurationTests {
 					assertThat(connectionFactory.getUserName()).isEqualTo("foo");
 					assertThat(connectionFactory.getPassword()).isEqualTo("bar");
 					assertThat(connectionFactory.getCloseTimeout()).isEqualTo(500);
-					assertThat(connectionFactory.isNonBlockingRedelivery())
-							.isTrue();
+					assertThat(connectionFactory.isNonBlockingRedelivery()).isTrue();
 					assertThat(connectionFactory.getSendTimeout()).isEqualTo(1000);
 					assertThat(connectionFactory.isTrustAllPackages()).isFalse();
 					assertThat(connectionFactory.getTrustedPackages())
@@ -177,23 +178,19 @@ public class ActiveMQAutoConfigurationTests {
 							.hasSize(1);
 					PooledConnectionFactory connectionFactory = context
 							.getBean(PooledConnectionFactory.class);
-					assertThat(connectionFactory.isBlockIfSessionPoolIsFull())
-							.isFalse();
+					assertThat(connectionFactory.isBlockIfSessionPoolIsFull()).isFalse();
 					assertThat(connectionFactory.getBlockIfSessionPoolIsFullTimeout())
 							.isEqualTo(64);
-					assertThat(connectionFactory.isCreateConnectionOnStartup())
-							.isFalse();
+					assertThat(connectionFactory.isCreateConnectionOnStartup()).isFalse();
 					assertThat(connectionFactory.getExpiryTimeout()).isEqualTo(4096);
 					assertThat(connectionFactory.getIdleTimeout()).isEqualTo(512);
 					assertThat(connectionFactory.getMaxConnections()).isEqualTo(256);
 					assertThat(connectionFactory.getMaximumActiveSessionPerConnection())
 							.isEqualTo(1024);
-					assertThat(connectionFactory.isReconnectOnException())
-							.isFalse();
+					assertThat(connectionFactory.isReconnectOnException()).isFalse();
 					assertThat(connectionFactory.getTimeBetweenExpirationCheckMillis())
 							.isEqualTo(2048);
-					assertThat(connectionFactory.isUseAnonymousProducers())
-							.isFalse();
+					assertThat(connectionFactory.isUseAnonymousProducers()).isFalse();
 				});
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/error/BasicErrorControllerIntegrationTests.java

@@ -51,6 +51,7 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.RequestEntity;
 import org.springframework.http.ResponseEntity;
+import org.springframework.util.StringUtils;
 import org.springframework.validation.BindException;
 import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -228,7 +229,7 @@ public class BasicErrorControllerIntegrationTests {
 			args.addAll(Arrays.asList(arguments));
 		}
 		this.context = SpringApplication.run(TestConfiguration.class,
-				args.toArray(new String[args.size()]));
+				StringUtils.toStringArray(args));
 	}
 
 	@Target(ElementType.TYPE)

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/SpringCli.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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 +96,7 @@ public final class SpringCli {
 				}
 			}
 		}
-		return urls.toArray(new URL[urls.size()]);
+		return urls.toArray(new URL[0]);
 	}
 
 }

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/CommandRunner.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -195,7 +195,7 @@ public class CommandRunner implements Iterable<Command> {
 			}
 			rtn.add(arg);
 		}
-		return rtn.toArray(new String[rtn.size()]);
+		return StringUtils.toStringArray(rtn);
 	}
 
 	/**

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/options/SourceOptions.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -25,6 +25,7 @@ import joptsimple.OptionSet;
 
 import org.springframework.boot.cli.util.ResourceUtils;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Extract source file options (anything following '--' in an {@link OptionSet}).
@@ -125,7 +126,11 @@ public class SourceOptions {
 	}
 
 	public String[] getArgsArray() {
-		return this.args.toArray(new String[this.args.size()]);
+		return this.args.stream().map(this::asString).toArray(String[]::new);
+	}
+
+	private String asString(Object arg) {
+		return (arg == null ? null : String.valueOf(arg));
 	}
 
 	public List<String> getSources() {
@@ -133,7 +138,7 @@ public class SourceOptions {
 	}
 
 	public String[] getSourcesArray() {
-		return this.sources.toArray(new String[this.sources.size()]);
+		return StringUtils.toStringArray(this.sources);
 	}
 
 }

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/shell/RunProcessCommand.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -24,6 +24,7 @@ import org.springframework.boot.cli.command.AbstractCommand;
 import org.springframework.boot.cli.command.Command;
 import org.springframework.boot.cli.command.status.ExitStatus;
 import org.springframework.boot.loader.tools.RunProcess;
+import org.springframework.util.StringUtils;
 
 /**
  * Special {@link Command} used to run a process from the shell. NOTE: this command is not
@@ -49,7 +50,7 @@ class RunProcessCommand extends AbstractCommand {
 
 	protected ExitStatus run(Collection<String> args) throws IOException {
 		this.process = new RunProcess(this.command);
-		int code = this.process.run(true, args.toArray(new String[args.size()]));
+		int code = this.process.run(true, StringUtils.toStringArray(args));
 		if (code == 0) {
 			return ExitStatus.OK;
 		}

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/DependencyManagementBomTransformation.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -169,7 +169,7 @@ public class DependencyManagementBomTransformation
 	private void updateDependencyResolutionContext(
 			List<Map<String, String>> bomDependencies) {
 		URI[] uris = Grape.getInstance().resolve(null,
-				bomDependencies.toArray(new Map[bomDependencies.size()]));
+				bomDependencies.toArray(new Map[0]));
 		DefaultModelBuilder modelBuilder = new DefaultModelBuilderFactory().newInstance();
 		for (URI uri : uris) {
 			try {

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/ExtendedGroovyClassLoader.java

@@ -186,7 +186,7 @@ public class ExtendedGroovyClassLoader extends GroovyClassLoader {
 				findGroovyJarsFromClassPath(urls);
 			}
 			Assert.state(!urls.isEmpty(), "Unable to find groovy JAR");
-			return new ArrayList<>(urls).toArray(new URL[urls.size()]);
+			return new ArrayList<>(urls).toArray(new URL[0]);
 		}
 
 		private void findGroovyJarsDirectly(ClassLoader classLoader, Set<URL> urls) {

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/GroovyCompiler.java

@@ -49,6 +49,7 @@ import org.springframework.boot.cli.compiler.grape.DependencyResolutionContext;
 import org.springframework.boot.cli.compiler.grape.GrapeEngineInstaller;
 import org.springframework.boot.cli.util.ResourceUtils;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.util.ClassUtils;
 
 /**
  * Compiler for Groovy sources. Primarily a simple Facade for
@@ -220,7 +221,7 @@ public class GroovyCompiler {
 			classes.add(0, mainClass);
 		}
 
-		return classes.toArray(new Class<?>[classes.size()]);
+		return ClassUtils.toClassArray(classes);
 	}
 
 	@SuppressWarnings("rawtypes")

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/AetherGrapeEngine.java

@@ -290,7 +290,7 @@ public class AetherGrapeEngine implements GrapeEngine {
 			for (File file : files) {
 				uris.add(file.toURI());
 			}
-			return uris.toArray(new URI[uris.size()]);
+			return uris.toArray(new URI[0]);
 		}
 		catch (Exception ex) {
 			throw new DependencyResolutionFailedException(ex);

spring-boot-project/spring-boot-cli/src/test/java/org/springframework/boot/cli/CliTester.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -43,6 +43,7 @@ import org.springframework.boot.cli.command.grab.GrabCommand;
 import org.springframework.boot.cli.command.run.RunCommand;
 import org.springframework.boot.test.rule.OutputCapture;
 import org.springframework.util.FileCopyUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link TestRule} that can be used to invoke CLI commands.
@@ -84,7 +85,7 @@ public class CliTester implements TestRule {
 					"--classpath=.:" + new File("target/test-classes").getAbsolutePath());
 		}
 		Future<RunCommand> future = submitCommand(new RunCommand(),
-				updatedArgs.toArray(new String[updatedArgs.size()]));
+				StringUtils.toStringArray(updatedArgs));
 		this.commands.add(future.get(this.timeout, TimeUnit.MILLISECONDS));
 		return getOutput();
 	}

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/DevToolsProperties.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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 DevToolsProperties {
 				allExclude.addAll(
 						StringUtils.commaDelimitedListToSet(this.additionalExclude));
 			}
-			return allExclude.toArray(new String[allExclude.size()]);
+			return StringUtils.toStringArray(allExclude);
 		}
 
 		public String getExclude() {

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/ChangeableUrls.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -79,7 +79,7 @@ final class ChangeableUrls implements Iterable<URL> {
 	}
 
 	public URL[] toArray() {
-		return this.urls.toArray(new URL[this.urls.size()]);
+		return this.urls.toArray(new URL[0]);
 	}
 
 	public List<URL> toList() {

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/ClassLoaderFilesResourcePatternResolver.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -119,7 +119,7 @@ final class ClassLoaderFilesResourcePatternResolver implements ResourcePatternRe
 			}
 		}
 		resources.addAll(getAdditionalResources(locationPattern));
-		return resources.toArray(new Resource[resources.size()]);
+		return resources.toArray(new Resource[0]);
 	}
 
 	private List<Resource> getAdditionalResources(String locationPattern)

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/Restarter.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -273,7 +273,7 @@ public class Restarter {
 
 	private Throwable doStart() throws Exception {
 		Assert.notNull(this.mainClassName, "Unable to find the main class to restart");
-		URL[] urls = this.urls.toArray(new URL[this.urls.size()]);
+		URL[] urls = this.urls.toArray(new URL[0]);
 		ClassLoaderFiles updatedFiles = new ClassLoaderFiles(this.classLoaderFiles);
 		ClassLoader classLoader = new RestartClassLoader(this.applicationClassLoader,
 				urls, updatedFiles, this.logger);

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/SpringBootMockMvcBuilderCustomizer.java

@@ -41,6 +41,7 @@ import org.springframework.test.web.servlet.result.PrintingResultHandler;
 import org.springframework.test.web.servlet.setup.ConfigurableMockMvcBuilder;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
 import org.springframework.web.context.WebApplicationContext;
 
 /**
@@ -133,7 +134,7 @@ public class SpringBootMockMvcBuilderCustomizer implements MockMvcBuilderCustomi
 			builder.addFilters(filter);
 		}
 		else {
-			builder.addFilter(filter, urls.toArray(new String[urls.size()]));
+			builder.addFilter(filter, StringUtils.toStringArray(urls));
 		}
 	}
 

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java

@@ -173,7 +173,7 @@ public class SpringBootContextLoader extends AbstractContextLoader {
 		if (!isEmbeddedWebEnvironment(config) && !hasCustomServerPort(properties)) {
 			properties.add("server.port=-1");
 		}
-		return properties.toArray(new String[properties.size()]);
+		return StringUtils.toStringArray(properties);
 	}
 
 	private void disableJmx(List<String> properties) {
@@ -187,9 +187,8 @@ public class SpringBootContextLoader extends AbstractContextLoader {
 
 	private ConfigurationPropertySource convertToConfigurationPropertySource(
 			List<String> properties) {
-		String[] array = properties.toArray(new String[properties.size()]);
-		return new MapConfigurationPropertySource(
-				TestPropertySourceUtils.convertInlinedPropertiesToMap(array));
+		return new MapConfigurationPropertySource(TestPropertySourceUtils
+				.convertInlinedPropertiesToMap(StringUtils.toStringArray(properties)));
 	}
 
 	/**

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootTestContextBootstrapper.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -52,6 +52,7 @@ import org.springframework.test.context.web.WebMergedContextConfiguration;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link TestContextBootstrapper} for Spring Boot. Provides support for
@@ -137,7 +138,7 @@ public class SpringBootTestContextBootstrapper extends DefaultTestContextBootstr
 		if (configAttributes.getClasses() != null) {
 			combined.addAll(Arrays.asList(configAttributes.getClasses()));
 		}
-		configAttributes.setClasses(combined.toArray(new Class<?>[combined.size()]));
+		configAttributes.setClasses(ClassUtils.toClassArray(combined));
 	}
 
 	@Override
@@ -153,8 +154,7 @@ public class SpringBootTestContextBootstrapper extends DefaultTestContextBootstr
 		List<String> propertySourceProperties = getAndProcessPropertySourceProperties(
 				mergedConfig);
 		mergedConfig = createModifiedConfig(mergedConfig, classes,
-				propertySourceProperties
-						.toArray(new String[propertySourceProperties.size()]));
+				StringUtils.toStringArray(propertySourceProperties));
 		WebEnvironment webEnvironment = getWebEnvironment(mergedConfig.getTestClass());
 		if (webEnvironment != null && isWebEnvironmentSupported(mergedConfig)) {
 			WebApplicationType webApplicationType = getWebApplicationType(mergedConfig);

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/mock/mockito/MockDefinition.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -28,6 +28,7 @@ import org.mockito.Mockito;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.style.ToStringCreator;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
@@ -147,7 +148,7 @@ class MockDefinition extends Definition {
 			settings.name(name);
 		}
 		if (!this.extraInterfaces.isEmpty()) {
-			settings.extraInterfaces(this.extraInterfaces.toArray(new Class<?>[] {}));
+			settings.extraInterfaces(ClassUtils.toClassArray(this.extraInterfaces));
 		}
 		settings.defaultAnswer(this.answer);
 		if (this.serializable) {

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/mock/mockito/MockitoPostProcessor.java

@@ -279,7 +279,7 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 			}
 		}
 		beans.removeIf(this::isScopedTarget);
-		return beans.toArray(new String[beans.size()]);
+		return StringUtils.toStringArray(beans);
 	}
 
 	private boolean isScopedTarget(String beanName) {

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/TestJarFile.java

@@ -123,7 +123,7 @@ public class TestJarFile {
 	public File getFile(String extension) throws IOException {
 		File file = this.temporaryFolder.newFile();
 		file = new File(file.getParent(), file.getName() + "." + extension);
-		ZipUtil.pack(this.entries.toArray(new ZipEntrySource[this.entries.size()]), file);
+		ZipUtil.pack(this.entries.toArray(new ZipEntrySource[0]), file);
 		return file;
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/Launcher.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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 abstract class Launcher {
 		for (Archive archive : archives) {
 			urls.add(archive.getUrl());
 		}
-		return createClassLoader(urls.toArray(new URL[urls.size()]));
+		return createClassLoader(urls.toArray(new URL[0]));
 	}
 
 	/**

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -369,7 +369,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 			addResources(urls);
 			addProjectClasses(urls);
 			addDependencies(urls);
-			return urls.toArray(new URL[urls.size()]);
+			return urls.toArray(new URL[0]);
 		}
 		catch (IOException ex) {
 			throw new MojoExecutionException("Unable to build classpath", ex);

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RepackageMojo.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -262,7 +262,7 @@ public class RepackageMojo extends AbstractDependencyFilterMojo {
 		if (!this.includeSystemScope) {
 			filters.add(new ScopeFilter(null, Artifact.SCOPE_SYSTEM));
 		}
-		return filters.toArray(new ArtifactsFilter[filters.size()]);
+		return filters.toArray(new ArtifactsFilter[0]);
 	}
 
 	private LaunchScript getLaunchScript() throws IOException {

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RunArguments.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -49,7 +49,7 @@ class RunArguments {
 	}
 
 	public String[] asArray() {
-		return this.args.toArray(new String[this.args.size()]);
+		return this.args.toArray(new String[0]);
 	}
 
 	private static String[] parseArgs(String arguments) {

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RunMojo.java

@@ -71,7 +71,7 @@ public class RunMojo extends AbstractRunMojo {
 					new JavaExecutable().toString());
 			Runtime.getRuntime()
 					.addShutdownHook(new Thread(new RunProcessKiller(runProcess)));
-			int exitCode = runProcess.run(true, args.toArray(new String[args.size()]));
+			int exitCode = runProcess.run(true, args.toArray(new String[0]));
 			if (exitCode == 0 || exitCode == EXIT_CODE_SIGINT) {
 				return;
 			}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/StartMojo.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -105,7 +105,7 @@ public class StartMojo extends AbstractRunMojo {
 		try {
 			RunProcess runProcess = new RunProcess(workingDirectory,
 					new JavaExecutable().toString());
-			runProcess.run(false, args.toArray(new String[args.size()]));
+			runProcess.run(false, args.toArray(new String[0]));
 			return runProcess;
 		}
 		catch (Exception ex) {

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/runner/classpath/ModifiedClassPathRunner.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -105,7 +105,7 @@ public class ModifiedClassPathRunner extends BlockJUnit4ClassRunner {
 				extractedUrls.add(url);
 			}
 		});
-		return extractedUrls.toArray(new URL[extractedUrls.size()]);
+		return extractedUrls.toArray(new URL[0]);
 	}
 
 	private Stream<URL> doExtractUrls(ClassLoader classLoader) throws Exception {
@@ -158,7 +158,7 @@ public class ModifiedClassPathRunner extends BlockJUnit4ClassRunner {
 				processedUrls.add(url);
 			}
 		}
-		return processedUrls.toArray(new URL[processedUrls.size()]);
+		return processedUrls.toArray(new URL[0]);
 	}
 
 	private List<URL> getAdditionalUrls(Class<?> testClass) throws Exception {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -380,7 +380,7 @@ public class SpringApplication {
 		// Load the sources
 		Set<Object> sources = getAllSources();
 		Assert.notEmpty(sources, "Sources must not be empty");
-		load(context, sources.toArray(new Object[sources.size()]));
+		load(context, sources.toArray(new Object[0]));
 		listeners.contextLoaded(context);
 	}
 
@@ -516,7 +516,7 @@ public class SpringApplication {
 		// But these ones should go first (last wins in a property key clash)
 		Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);
 		profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
-		environment.setActiveProfiles(profiles.toArray(new String[profiles.size()]));
+		environment.setActiveProfiles(StringUtils.toStringArray(profiles));
 	}
 
 	private void configureIgnoreBeanInfo(ConfigurableEnvironment environment) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java

@@ -37,6 +37,7 @@ import org.springframework.context.ApplicationListener;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.ResourceLoader;
+import org.springframework.util.StringUtils;
 
 /**
  * Builder for {@link SpringApplication} and {@link ApplicationContext} instances with
@@ -455,16 +456,16 @@ public class SpringApplicationBuilder {
 	 */
 	public SpringApplicationBuilder profiles(String... profiles) {
 		this.additionalProfiles.addAll(Arrays.asList(profiles));
-		this.application.setAdditionalProfiles(this.additionalProfiles
-				.toArray(new String[this.additionalProfiles.size()]));
+		this.application.setAdditionalProfiles(
+				StringUtils.toStringArray(this.additionalProfiles));
 		return this;
 	}
 
 	private SpringApplicationBuilder additionalProfiles(
 			Collection<String> additionalProfiles) {
 		this.additionalProfiles = new LinkedHashSet<>(additionalProfiles);
-		this.application.setAdditionalProfiles(this.additionalProfiles
-				.toArray(new String[this.additionalProfiles.size()]));
+		this.application.setAdditionalProfiles(
+				StringUtils.toStringArray(this.additionalProfiles));
 		return this;
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/annotation/Configurations.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -26,6 +26,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Configuration;
@@ -34,6 +35,7 @@ import org.springframework.core.OrderComparator;
 import org.springframework.core.Ordered;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
  * A set of {@link Configuration @Configuration} classes that can be registered in
@@ -114,12 +116,17 @@ public abstract class Configurations {
 	 * @return configuration classes in registration order
 	 */
 	public static Class<?>[] getClasses(Collection<Configurations> configurations) {
-		List<Configurations> orderedConfigurations = new ArrayList<>(configurations);
-		orderedConfigurations.sort(COMPARATOR);
-		List<Configurations> collated = collate(orderedConfigurations);
-		return collated.stream().flatMap((c) -> c.getClasses().stream())
-				.collect(Collectors.toCollection(LinkedHashSet::new))
-				.toArray(new Class<?>[0]);
+		List<Configurations> ordered = new ArrayList<>(configurations);
+		ordered.sort(COMPARATOR);
+		List<Configurations> collated = collate(ordered);
+		LinkedHashSet<Class<?>> classes = collated.stream()
+				.flatMap(Configurations::streamClasses)
+				.collect(Collectors.toCollection(LinkedHashSet::new));
+		return ClassUtils.toClassArray(classes);
+	}
+
+	private static Stream<Class<?>> streamClasses(Configurations configurations) {
+		return configurations.getClasses().stream();
 	}
 
 	private static List<Configurations> collate(

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -565,7 +565,7 @@ public class ConfigFileApplicationListener
 			// But this one should go first (last wins in a property key clash)
 			profiles.add(profile.getName());
 			profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
-			environment.setActiveProfiles(profiles.toArray(new String[profiles.size()]));
+			environment.setActiveProfiles(StringUtils.toStringArray(profiles));
 		}
 
 		private Set<String> getSearchLocations() {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBinder.java

@@ -113,7 +113,7 @@ class ConfigurationPropertiesBinder {
 		}
 		if (!validators.isEmpty()) {
 			handler = new ValidationBindHandler(handler,
-					validators.toArray(new Validator[validators.size()]));
+					validators.toArray(new Validator[0]));
 		}
 		return handler;
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java

@@ -460,8 +460,7 @@ public final class ConfigurationPropertyName
 				elements.add(elementValue);
 			}
 		});
-		return new ConfigurationPropertyName(
-				elements.toArray(new CharSequence[elements.size()]));
+		return new ConfigurationPropertyName(elements.toArray(new CharSequence[0]));
 	}
 
 	/**
@@ -508,8 +507,7 @@ public final class ConfigurationPropertyName
 				elements.add(elementValue);
 			}
 		});
-		return new ConfigurationPropertyName(
-				elements.toArray(new CharSequence[elements.size()]));
+		return new ConfigurationPropertyName(elements.toArray(new CharSequence[0]));
 	}
 
 	private static void process(CharSequence name, char separator,

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringIterableConfigurationPropertySource.java

@@ -121,7 +121,7 @@ class SpringIterableConfigurationPropertySource extends SpringConfigurationPrope
 				mappings.add(mapping);
 			}
 		}
-		result = mappings.toArray(new PropertyMapping[mappings.size()]);
+		result = mappings.toArray(new PropertyMapping[0]);
 		if (cache != null) {
 			cache.setMappings(result);
 		}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/jta/atomikos/AtomikosDependsOnBeanFactoryPostProcessor.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -29,6 +29,7 @@ import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.core.Ordered;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link BeanFactoryPostProcessor} to automatically setup the recommended
@@ -65,7 +66,7 @@ public class AtomikosDependsOnBeanFactoryPostProcessor
 		addDependencies(beanFactory, "javax.jms.ConnectionFactory", dependsOn);
 		addDependencies(beanFactory, "javax.sql.DataSource", dependsOn);
 		if (dependsOn.size() != initialSize) {
-			bean.setDependsOn(dependsOn.toArray(new String[dependsOn.size()]));
+			bean.setDependsOn(StringUtils.toStringArray(dependsOn));
 		}
 	}
 
@@ -77,7 +78,7 @@ public class AtomikosDependsOnBeanFactoryPostProcessor
 			BeanDefinition bean = beanFactory.getBeanDefinition(messageDrivenContainer);
 			Set<String> dependsOn = new LinkedHashSet<>(asList(bean.getDependsOn()));
 			dependsOn.addAll(asList(transactionManagers));
-			bean.setDependsOn(dependsOn.toArray(new String[dependsOn.size()]));
+			bean.setDependsOn(StringUtils.toStringArray(dependsOn));
 		}
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystem.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -119,8 +119,7 @@ public class Log4J2LoggingSystem extends Slf4JLoggingSystem {
 			Collections.addAll(supportedConfigLocations, "log4j2.json", "log4j2.jsn");
 		}
 		supportedConfigLocations.add("log4j2.xml");
-		return supportedConfigLocations
-				.toArray(new String[supportedConfigLocations.size()]);
+		return StringUtils.toStringArray(supportedConfigLocations);
 	}
 
 	protected boolean isClassAvailable(String className) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/orm/jpa/EntityManagerFactoryBuilder.java

@@ -30,6 +30,7 @@ import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.persistenceunit.PersistenceUnitManager;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * Convenient builder for JPA EntityManagerFactory instances. Collects common
@@ -142,7 +143,7 @@ public class EntityManagerFactoryBuilder {
 			for (Class<?> type : basePackageClasses) {
 				packages.add(ClassUtils.getPackageName(type));
 			}
-			this.packagesToScan = packages.toArray(new String[0]);
+			this.packagesToScan = StringUtils.toStringArray(packages);
 			return this;
 		}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/jetty/JettyServletWebServerFactory.java

@@ -277,8 +277,8 @@ public class JettyServletWebServerFactory extends AbstractServletWebServerFactor
 					resources.add(resource);
 				}
 			}
-			handler.setBaseResource(new ResourceCollection(
-					resources.toArray(new Resource[resources.size()])));
+			handler.setBaseResource(
+					new ResourceCollection(resources.toArray(new Resource[0])));
 		}
 		catch (Exception ex) {
 			throw new IllegalStateException(ex);
@@ -343,7 +343,7 @@ public class JettyServletWebServerFactory extends AbstractServletWebServerFactor
 		configurations.addAll(getConfigurations());
 		configurations.add(getErrorPageConfiguration());
 		configurations.add(getMimeTypeConfiguration());
-		return configurations.toArray(new Configuration[configurations.size()]);
+		return configurations.toArray(new Configuration[0]);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowCompressionConfigurer.java

@@ -74,7 +74,7 @@ final class UndertowCompressionConfigurer {
 				predicates.add(Predicates.not(Predicates.regex(agentHeader, agent)));
 			}
 		}
-		return predicates.toArray(new Predicate[predicates.size()]);
+		return predicates.toArray(new Predicate[0]);
 	}
 
 	private static class CompressibleMimeTypePredicate implements Predicate {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java

@@ -387,7 +387,7 @@ public class UndertowServletWebServerFactory extends AbstractServletWebServerFac
 		}
 		resourceManagers.add(new MetaInfResourcesResourceManager(resourceJarUrls));
 		return new CompositeResourceManager(
-				resourceManagers.toArray(new ResourceManager[resourceManagers.size()]));
+				resourceManagers.toArray(new ResourceManager[0]));
 	}
 
 	private File getCanonicalDocumentRoot(File docBase) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/AnnotationConfigReactiveWebApplicationContext.java

@@ -233,8 +233,7 @@ public class AnnotationConfigReactiveWebApplicationContext
 					+ StringUtils.collectionToCommaDelimitedString(this.annotatedClasses)
 					+ "]");
 		}
-		reader.register(this.annotatedClasses
-				.toArray(new Class<?>[this.annotatedClasses.size()]));
+		reader.register(ClassUtils.toClassArray(this.annotatedClasses));
 	}
 
 	private void scanBasePackages(ClassPathBeanDefinitionScanner scanner) {
@@ -243,7 +242,7 @@ public class AnnotationConfigReactiveWebApplicationContext
 					+ StringUtils.collectionToCommaDelimitedString(this.basePackages)
 					+ "]");
 		}
-		scanner.scan(this.basePackages.toArray(new String[this.basePackages.size()]));
+		scanner.scan(StringUtils.toStringArray(this.basePackages));
 	}
 
 	private void registerConfigLocations(AnnotatedBeanDefinitionReader reader,

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/AnnotationConfigReactiveWebServerApplicationContext.java

@@ -33,6 +33,7 @@ import org.springframework.context.annotation.ScopeMetadataResolver;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -209,8 +210,7 @@ public class AnnotationConfigReactiveWebServerApplicationContext
 			this.scanner.scan(this.basePackages);
 		}
 		if (!this.annotatedClasses.isEmpty()) {
-			this.reader.register(this.annotatedClasses
-					.toArray(new Class<?>[this.annotatedClasses.size()]));
+			this.reader.register(ClassUtils.toClassArray(this.annotatedClasses));
 		}
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/AbstractFilterRegistrationBean.java

@@ -33,6 +33,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Abstract base {@link ServletContextInitializer} to register {@link Filter}s in a
@@ -249,13 +250,13 @@ abstract class AbstractFilterRegistrationBean<T extends Filter>
 				this.logger.info("Mapping filter: '" + registration.getName()
 						+ "' to servlets: " + servletNames);
 				registration.addMappingForServletNames(dispatcherTypes, this.matchAfter,
-						servletNames.toArray(new String[servletNames.size()]));
+						StringUtils.toStringArray(servletNames));
 			}
 			if (!this.urlPatterns.isEmpty()) {
 				this.logger.info("Mapping filter: '" + registration.getName()
 						+ "' to urls: " + this.urlPatterns);
 				registration.addMappingForUrlPatterns(dispatcherTypes, this.matchAfter,
-						this.urlPatterns.toArray(new String[this.urlPatterns.size()]));
+						StringUtils.toStringArray(this.urlPatterns));
 			}
 		}
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/ServletRegistrationBean.java

@@ -31,6 +31,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * A {@link ServletContextInitializer} to register {@link Servlet}s in a Servlet 3.0+
@@ -193,8 +194,7 @@ public class ServletRegistrationBean<T extends Servlet>
 	@Override
 	protected void configure(ServletRegistration.Dynamic registration) {
 		super.configure(registration);
-		String[] urlMapping = this.urlMappings
-				.toArray(new String[this.urlMappings.size()]);
+		String[] urlMapping = StringUtils.toStringArray(this.urlMappings);
 		if (urlMapping.length == 0 && this.alwaysMapUrl) {
 			urlMapping = DEFAULT_MAPPINGS;
 		}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/AnnotationConfigServletWebServerApplicationContext.java

@@ -32,6 +32,7 @@ import org.springframework.context.annotation.ScopeMetadataResolver;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 
 /**
@@ -206,8 +207,7 @@ public class AnnotationConfigServletWebServerApplicationContext
 			this.scanner.scan(this.basePackages);
 		}
 		if (!this.annotatedClasses.isEmpty()) {
-			this.reader.register(this.annotatedClasses
-					.toArray(new Class<?>[this.annotatedClasses.size()]));
+			this.reader.register(ClassUtils.toClassArray(this.annotatedClasses));
 		}
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/server/AbstractServletWebServerFactory.java

@@ -255,8 +255,7 @@ public abstract class AbstractServletWebServerFactory
 		mergedInitializers.add(new SessionConfiguringInitializer(this.session));
 		mergedInitializers.addAll(Arrays.asList(initializers));
 		mergedInitializers.addAll(this.initializers);
-		return mergedInitializers
-				.toArray(new ServletContextInitializer[mergedInitializers.size()]);
+		return mergedInitializers.toArray(new ServletContextInitializer[0]);
 	}
 
 	/**

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SimpleMainTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -83,7 +83,7 @@ public class SimpleMainTests {
 			list.add("--spring.main.sources="
 					+ StringUtils.arrayToCommaDelimitedString(args));
 		}
-		return list.toArray(new String[list.size()]);
+		return StringUtils.toStringArray(list);
 	}
 
 	private String getOutput() {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java

@@ -213,7 +213,7 @@ public class ConfigurationPropertiesTests {
 		for (int i = 0; i < 1000; i++) {
 			pairs.add("list[" + i + "]:" + i);
 		}
-		load(BasicConfiguration.class, pairs.toArray(new String[] {}));
+		load(BasicConfiguration.class, StringUtils.toStringArray(pairs));
 		BasicProperties bean = this.context.getBean(BasicProperties.class);
 		assertThat(bean.list).hasSize(1000);
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/env/YamlPropertySourceLoaderTests.java

@@ -27,6 +27,7 @@ import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -64,7 +65,7 @@ public class YamlPropertySourceLoaderTests {
 				.load("resource", resource, null, (profile) -> true);
 		assertThat(source).isNotNull();
 		assertThat(source.getPropertyNames())
-				.isEqualTo(expected.toArray(new String[] {}));
+				.isEqualTo(StringUtils.toStringArray(expected));
 	}
 
 	@Test

spring-boot-samples/spring-boot-sample-jooq/src/main/java/sample/jooq/JooqExamples.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -65,7 +65,7 @@ public class JooqExamples implements CommandLineRunner {
 		Query query = this.dsl.select(BOOK.TITLE, AUTHOR.FIRST_NAME, AUTHOR.LAST_NAME)
 				.from(BOOK).join(AUTHOR).on(BOOK.AUTHOR_ID.equal(AUTHOR.ID))
 				.where(BOOK.PUBLISHED_IN.equal(2015));
-		Object[] bind = query.getBindValues().toArray(new Object[] {});
+		Object[] bind = query.getBindValues().toArray(new Object[0]);
 		List<String> list = this.jdbc.query(query.getSQL(), bind,
 				new RowMapper<String>() {
 					@Override

spring-boot-tests/spring-boot-integration-tests/spring-boot-devtools-tests/src/test/java/org/springframework/boot/devtools/tests/JvmLauncher.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -26,6 +26,8 @@ import org.junit.rules.TestRule;
 import org.junit.runner.Description;
 import org.junit.runners.model.Statement;
 
+import org.springframework.util.StringUtils;
+
 /**
  * JUnit {@link TestRule} that launched a JVM and redirects its output to a test
  * method-specific location.
@@ -50,7 +52,7 @@ class JvmLauncher implements TestRule {
 		command.addAll(Arrays.asList(args));
 		File standardOut = new File(this.outputDirectory, name + ".out");
 		File standardError = new File(this.outputDirectory, name + ".err");
-		Process process = new ProcessBuilder(command.toArray(new String[command.size()]))
+		Process process = new ProcessBuilder(StringUtils.toStringArray(command))
 				.redirectError(standardError).redirectOutput(standardOut).start();
 		return new LaunchedJvm(process, standardOut, standardError);
 	}

spring-boot-tests/spring-boot-integration-tests/spring-boot-server-tests/src/test/java/org/springframework/boot/context/embedded/AbstractApplicationLauncher.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -25,6 +25,7 @@ import java.util.List;
 import org.junit.rules.ExternalResource;
 
 import org.springframework.util.FileCopyUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * Base {@link ExternalResource} for launching a Spring Boot application as part of a
@@ -74,7 +75,7 @@ abstract class AbstractApplicationLauncher extends ExternalResource {
 		arguments.add(System.getProperty("java.home") + "/bin/java");
 		arguments.addAll(getArguments(archive));
 		ProcessBuilder processBuilder = new ProcessBuilder(
-				arguments.toArray(new String[arguments.size()]));
+				StringUtils.toStringArray(arguments));
 		processBuilder.redirectOutput(Redirect.INHERIT);
 		processBuilder.redirectError(Redirect.INHERIT);
 		if (workingDirectory != null) {

spring-boot-tests/spring-boot-integration-tests/spring-boot-server-tests/src/test/java/org/springframework/boot/context/embedded/AbstractEmbeddedServletContainerIntegrationTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -53,7 +53,7 @@ public abstract class AbstractEmbeddedServletContainerIntegrationTests {
 		parameters.addAll(createParameters(packaging, "jetty", applicationLaunchers));
 		parameters.addAll(createParameters(packaging, "tomcat", applicationLaunchers));
 		parameters.addAll(createParameters(packaging, "undertow", applicationLaunchers));
-		return parameters.toArray(new Object[parameters.size()]);
+		return parameters.toArray(new Object[0]);
 	}
 
 	private static List<Object> createParameters(String packaging, String container,