Fixed all possible warnings (mainly by solving generics issues). Added keyword final where suitable. Added annotation @Override were suitable. Enhanced logging on problematic test by adding name of countdown latch.
Fixed ProblematicTest by using a ConcurrentHashMap instead of a HashMap.
Added support for Runnable and Callable with null as result.
Optimized support for Runnable and Callable with null as result with extended ConcurrentHashMap class.
After some discussions with Christoph we decided to use Collections.synchronizedMap() in this case, although it is not a beautiful solution.
Removed final keyword from parameter lists.
Removed final keyword from variables. Split up {} to two lines.
Fixed import wildcard.
Merge branch 'master' of https://github.com/hazelcast/hazelcast
Some last code cleanup according to changes in other test packages (see #2983).
Merge branch 'master' of https://github.com/Donnerbart/hazelcast into fixFor2950
Merge pull request #2950 from Donnerbart/master

Concurrency issue in getExecutorService.submitToMembers()