code: public static synchronized void returnConnectionListener(String poolName, Object mcp,
                                                              Object cl, boolean kill, boolean interleaving,
                                                              Throwable callstack)
     {
        if (!interleaving)
        {
           if (!kill)
           {
              log.tracef("%s", new TraceEvent(poolName,
                                              Integer.toHexString(System.identityHashCode(mcp)),
                                              TraceEvent.RETURN_CONNECTION_LISTENER,
                                              Integer.toHexString(System.identityHashCode(cl)),
                                              !confidential && callstack != null ? toString(callstack) : ""));
           }
           else
           {
              log.tracef("%s", new TraceEvent(poolName,
                                              Integer.toHexString(System.identityHashCode(mcp)),
                                              TraceEvent.RETURN_CONNECTION_LISTENER_WITH_KILL,
                                              Integer.toHexString(System.identityHashCode(cl)),
                                              !confidential && callstack != null ? toString(callstack) : ""));
           }
        }
        else
        {
           if (!kill)
           {
              log.tracef("%s", new TraceEvent(poolName,
                                              Integer.toHexString(System.identityHashCode(mcp)),
                                              TraceEvent.RETURN_INTERLEAVING_CONNECTION_LISTENER,
                                              Integer.toHexString(System.identityHashCode(cl)),
                                              !confidential && callstack != null ? toString(callstack) : ""));
           }
           else
           {
              log.tracef("%s", new TraceEvent(poolName,
                                              Integer.toHexString(System.identityHashCode(mcp)),
                                              TraceEvent.RETURN_INTERLEAVING_CONNECTION_LISTENER_WITH_KILL,
                                              Integer.toHexString(System.identityHashCode(cl)),
                                              !confidential && callstack != null ? toString(callstack) : ""));
           }
        }
     }
docs: Return connection listener
  @param poolName The name of the pool
  @param mcp The managed connection pool
  @param cl The connection listener
  @param kill Kill the listener
  @param interleaving Interleaving flag
  @param callstack The call stack