code: public boolean hasReadLock(TransactionImpl tx, Object obj)
      {
          checkTimedOutLocks();
  
          Identity oid = new Identity(obj,getBroker());
          String oidString = oid.toString();
  		String txGuid = tx.getGUID();
          return hasReadLockInternal(oidString, txGuid);
      }
docs: check if there is a reader lock entry for transaction tx on object obj
  in the persistent storage.