docs: public synchronized Object lastKey(Transaction transaction)
                      throws ObjectManagerException
      {
          if (Tracing.isAnyTracingEnabled() && trace.isEntryEnabled())
              trace.entry(this,
                          cclass,
                          "lastKey",
                          new Object[] { transaction });
  
          Entry entry = lastEntry(transaction);
          Object returnKey = entry.getKey();
  
          if (Tracing.isAnyTracingEnabled() && trace.isEntryEnabled())
              trace.exit(this,
                         cclass,
                         "lastKey",
                         new Object[] { returnKey });
          return returnKey;
      }