@Override
  @Nullable
  public Set<InternalDistributedMember> putOutgoing(final @NotNull DistributionMessage msg) {
    try {
      DistributionMessageObserver observer = DistributionMessageObserver.getInstance();
      if (observer != null) {
        observer.beforeSendMessage(this, msg);
      }
      return sendMessage(msg);
    } catch (NotSerializableException e) {
      throw new InternalGemFireException(e);
    }
  }
Returns the identity of this <code>DistributionManager</code>
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterDistributionManager.java