DATAREDIS-383 - Improve JavaDoc of RedisCacheManager.

Extended description on setCacheNames(..). Original pull request: spring-projects#132.

Author: snicoll

src/main/java/org/springframework/data/redis/cache/RedisCacheManager.java

@@ -106,7 +106,9 @@ public Cache getCache(String name) {
 /**
  * Specify the set of cache names for this CacheManager's 'static' mode. <br>
  * The number of caches and their names will be fixed after a call to this method, with no creation of further cache
- * regions at runtime.
+ * regions at runtime. <br>
+ * Calling this with a {@code null} or empty collection argument resets the mode to 'dynamic', allowing for further
+ * creation of caches again.
  */
 public void setCacheNames(Collection<String> cacheNames) {