refactored client requests used in client executor service
small clean up
fixed checkstyle error
fixed checkstyle error
Make ClockImpl abstraction public to allow external Clock implementations to be used.  Introduced new com.hazelcast.clock.impl system property.
Added test to cluster behaviour when system clock changes backward / forward.
When system clock jump is greater than 'maxNoMasterConfirmationMillis', master incorrectly kicks out some members because of master confirmation timeout. Master confirmations should be reset when a huge clock jump is detected to avoid this.
No need to send 'master-time' via partition table publish, it's not used anymore.
Improved readability of code for IMap.values() and IMap.values(Predicate), e.g. newlines, moved declarations to usage, new sub-methods. Sorted methods per superclass and/or from public to private. Added @Override to methods.
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Merge pull request #4326 from mdogan/heartbeat

Reset master confirmations when system clock changes significantly
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