return null instead of throwing an exception when pid is not found in store
Reverting previous @Overrides chanrge from r6470, as that is the desiredbehavior under Java 1.6 -- previous versions of Java (e.g., 1.5) will notcomile with this usage of the @Overrides annotation, but the currentlysupported version will. So reverting to the 1.6 convention.
Removing incorrect @Override annotations that were preventing compilation. The methods marked did not actually override a method in the superclass, so they were not compiling. I think @Overrides was being mistaken for methods that implement an interface but aren't actually in the superclass.
throw RuntimeExceptions when store() methods throw declared exceptions -- we want callers to put() to be alerted if there are errors.
check if system metadata exists rather than just the id mapping (before creating the entry)
handle entryAdded (to hzSystemMetadata) to store sysmeta to local store when it is not already present
use HashMap, HashSet instead of the Tree* classes that require Identifier objects implement Comparable
added HazelCast MapStore and MapLoader implementation for SystemMetadata