Memory leak on every cache write.operation

Every cache write operation in a steady state (no state transfer) will write a copy of the key to StateConsumerImpl::updatedKey set. This set is intended to be null during steady state, but it is erroneously being created on a CH_UPDATE with a pendingCH of null.

These keys are not removed during a cache remove operation.

When enough keys are written to the cache, the container will OOM.