public boolean unregisterListener(final SignalListener listener) {
    boolean unregistered = false;

    for (Signal signal : Signal.values()) {
      unregistered |= unregisterListener(listener, signal);
    }

    return unregistered;
  }
Map used to register SignalListeners with SignalHandlers...
geode-core/src/main/java/org/apache/geode/internal/process/signal/AbstractSignalNotificationHandler.java