Added in NDB 7.4.3, this method supersedes
getLatestGCI(), which is
now deprecated and subject to removal in a future NDB Cluster
Prior to NDB 7.4.7, this method returned the highest epoch number
in the event queue. In NDB 7.4.7 and later, it returns the highest
epoch number found after calling
Uint64 getHighestQueuedEpoch ( void )
Return value. The most recent epoch number, an integer.