code: public int ensureInitiatorIsKnown(long initiatorId) {
          int newInitiatorCount = 0;
          if (m_initiatorData.get(initiatorId) == null) {
              m_initiatorData.put(initiatorId, new LastInitiatorData());
              newInitiatorCount++;
          }
          return newInitiatorCount;
      }
docs: After a catalog change, double check that all initators in the catalog
  that are known to be "up" are here, in the RPQ's list.
  @param initiatorId Initiator present in the catalog.
  @return The number of initiators that weren't known