Javadoc
Handles the local request to invalidate the key from this region.
Steps:
1) Locates the bucket region. If it doesnt find the actual bucket, it means
that this bucket is remapped to some other node and remappedBucketException
is thrown
2) get the existing value for the key from bucket region
3) if step 2 returns null, throw EntryNotFoundException
4) if step 2 returns non-null value, perform invalidate on the bucket
region and use value from step 2 in step 5
5) updateBucket2Size if bucket is on more than 1 node or else bucket
listners would take care of size update.