@Override
  public DistributionManager getDM() {
    InternalDistributedSystem sys = system;
    if (sys == null) {
      return null;
    }
    return sys.getDistributionManager();
  }
Creates a new {@link InternalDistributedSystem} connection for this agent. If one alread
exists, it is {@code disconnected} and a new one is created.
geode-core/src/main/java/org/apache/geode/internal/admin/remote/RemoteGfManagerAgent.java