default long getExclusiveLockProcIdOwner() {
    Procedure<?> proc = getExclusiveLockOwnerProcedure();
    return proc != null ? proc.getProcId() : -1L;
  }
Return the id of the procedure which holds the exclusive lock, if exists. Or a negative value
which means no one holds the exclusive lock.
<p/>
Notice that, in HBase, we assume that the procedure id is positive, or at least non-negative.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/LockStatus.java