Statically imported method was shadowed by member method on newer compilers
ISPN-4363 Add documentation for Cluster Listeners

* Added documentation about cluster listeners
* Added documentation about filters
* Added documentation about retry
ISPN-4323 ConditionalOperationsConcurrentWriteSkewTest fails randomly

* Changed 500 invocation tests to stress as they can last for minutes
* Moved more simple test to separate file and still functional
ISPN-3938 AdvancedAsyncCacheLoader.process() concurrency issues

Simplify ExecutorAllCompletionService to track the tasks itself instead of
using an ExecutorCompletionService.