diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/BeanFactoryAnnotationUtils.java b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/BeanFactoryAnnotationUtils.java
index a3f8791a55..9637abc94b 100644
--- a/spring-beans/src/main/java/org/springframework/beans/factory/annotation/BeanFactoryAnnotationUtils.java
+++ b/spring-beans/src/main/java/org/springframework/beans/factory/annotation/BeanFactoryAnnotationUtils.java
@@ -92,12 +92,12 @@ public class BeanFactoryAnnotationUtils {
 			return matchingBean;
 		}
 		else if (bf.containsBean(qualifier)) {
-			// Fallback: target bean at least found by bean name.
+			// Fallback: target bean at least found by bean name - probably a manually registered singleton.
 			return bf.getBean(qualifier, beanType);
 		}
 		else {
 			throw new NoSuchBeanDefinitionException(qualifier, "No matching " + beanType.getSimpleName() +
-					" bean found for qualifier '" + qualifier + "' - neither qualifier " + "match nor bean name match!");
+					" bean found for qualifier '" + qualifier + "' - neither qualifier match nor bean name match!");
 		}
 	}
 
@@ -133,7 +133,7 @@ public class BeanFactoryAnnotationUtils {
 				}
 			}
 			catch (NoSuchBeanDefinitionException ex) {
-				// ignore - can't compare qualifiers for a manually registered singleton object
+				// Ignore - can't compare qualifiers for a manually registered singleton object
 			}
 		}
 		return false;
diff --git a/spring-context-support/src/main/java/org/springframework/cache/guava/GuavaCache.java b/spring-context-support/src/main/java/org/springframework/cache/guava/GuavaCache.java
index 6acc2aad0b..302e513fcb 100644
--- a/spring-context-support/src/main/java/org/springframework/cache/guava/GuavaCache.java
+++ b/spring-context-support/src/main/java/org/springframework/cache/guava/GuavaCache.java
@@ -46,19 +46,22 @@ public class GuavaCache implements Cache {
 
 
 	/**
-	 * Create a {@link GuavaCache} instance.
+	 * Create a {@link GuavaCache} instance with the specified name and the
+	 * given internal {@link com.google.common.cache.Cache} to use.
 	 * @param name the name of the cache
-	 * @param cache backing Guava Cache instance
+	 * @param cache the backing Guava Cache instance
 	 */
 	public GuavaCache(String name, com.google.common.cache.Cache<Object, Object> cache) {
 		this(name, cache, true);
 	}
 
 	/**
-	 * Create a {@link GuavaCache} instance.
+	 * Create a {@link GuavaCache} instance with the specified name and the
+	 * given internal {@link com.google.common.cache.Cache} to use.
 	 * @param name the name of the cache
-	 * @param cache backing Guava Cache instance
-	 * @param allowNullValues whether to accept and convert null values for this cache
+	 * @param cache the backing Guava Cache instance
+	 * @param allowNullValues whether to accept and convert {@code null}
+	 * values for this cache
 	 */
 	public GuavaCache(String name, com.google.common.cache.Cache<Object, Object> cache, boolean allowNullValues) {
 		Assert.notNull(name, "Name must not be null");
@@ -110,8 +113,9 @@ public class GuavaCache implements Cache {
 			PutIfAbsentCallable callable = new PutIfAbsentCallable(value);
 			Object result = this.cache.get(key, callable);
 			return (callable.called ? null : toWrapper(result));
-		} catch (ExecutionException e) {
-			throw new IllegalArgumentException(e);
+		}
+		catch (ExecutionException ex) {
+			throw new IllegalStateException(ex);
 		}
 	}
 
@@ -161,19 +165,21 @@ public class GuavaCache implements Cache {
 	private static class NullHolder implements Serializable {
 	}
 
+
 	private class PutIfAbsentCallable implements Callable<Object> {
-		private boolean called;
 
 		private final Object value;
 
-		private PutIfAbsentCallable(Object value) {
+		private boolean called;
+
+		public PutIfAbsentCallable(Object value) {
 			this.value = value;
 		}
 
 		@Override
 		public Object call() throws Exception {
-			called = true;
-			return toStoreValue(value);
+			this.called = true;
+			return toStoreValue(this.value);
 		}
 	}
 
diff --git a/spring-context/src/main/java/org/springframework/cache/Cache.java b/spring-context/src/main/java/org/springframework/cache/Cache.java
index 61058eace1..8a8ee5537c 100644
--- a/spring-context/src/main/java/org/springframework/cache/Cache.java
+++ b/spring-context/src/main/java/org/springframework/cache/Cache.java
@@ -81,8 +81,8 @@ public interface Cache {
 	void put(Object key, Object value);
 
 	/**
-	 * Atomically associate the specified value with the specified key in this cache if
-	 * it is not set already.
+	 * Atomically associate the specified value with the specified key in this cache
+	 * if it is not set already.
 	 * <p>This is equivalent to:
 	 * <pre><code>
 	 * Object existingValue = cache.get(key);
@@ -93,17 +93,18 @@ public interface Cache {
 	 *     return existingValue;
 	 * }
 	 * </code></pre>
-	 * except that the action is performed atomically. While all known providers are
-	 * able to perform the put atomically, the returned value may be retrieved after
-	 * the attempt to put (i.e. in a non atomic way). Check the documentation of
-	 * the native cache implementation that you are using for more details.
+	 * except that the action is performed atomically. While all out-of-the-box
+	 * {@link CacheManager} implementations are able to perform the put atomically,
+	 * the operation may also be implemented in two steps, e.g. with a check for
+	 * presence and a subsequent put, in a non-atomic way. Check the documentation
+	 * of the native cache implementation that you are using for more details.
 	 * @param key the key with which the specified value is to be associated
 	 * @param value the value to be associated with the specified key
-	 * @return the value to which this cache maps the specified key (which may
-	 * be {@code null} itself), or also {@code null} if  the cache did not contain
-	 * any mapping for that key prior to this call. Returning {@code null} is
-	 * therefore an indicator that the given {@code value} has been associated
-	 * with the key
+	 * @return the value to which this cache maps the specified key (which may be
+	 * {@code null} itself), or also {@code null} if the cache did not contain any
+	 * mapping for that key prior to this call. Returning {@code null} is therefore
+	 * an indicator that the given {@code value} has been associated with the key.
+	 * @since 4.1
 	 */
 	ValueWrapper putIfAbsent(Object key, Object value);
 
diff --git a/spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCache.java b/spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCache.java
index 8601245ea8..07f50d7497 100644
--- a/spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCache.java
+++ b/spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCache.java
@@ -63,7 +63,8 @@ public class ConcurrentMapCache implements Cache {
 	/**
 	 * Create a new ConcurrentMapCache with the specified name.
 	 * @param name the name of the cache
-	 * @param allowNullValues whether to accept and convert null values for this cache
+	 * @param allowNullValues whether to accept and convert {@code null}
+	 * values for this cache
 	 */
 	public ConcurrentMapCache(String name, boolean allowNullValues) {
 		this(name, new ConcurrentHashMap<Object, Object>(256), allowNullValues);
@@ -71,7 +72,7 @@ public class ConcurrentMapCache implements Cache {
 
 	/**
 	 * Create a new ConcurrentMapCache with the specified name and the
-	 * given internal ConcurrentMap to use.
+	 * given internal {@link ConcurrentMap} to use.
 	 * @param name the name of the cache
 	 * @param store the ConcurrentMap to use as an internal store
 	 * @param allowNullValues whether to allow {@code null} values