@Override
  public Object handleRequest(Object request) {
    Object response = null;

    if (request instanceof RemoteLocatorJoinRequest) {
      response = updateAllLocatorInfo((RemoteLocatorJoinRequest) request);
    } else if (request instanceof LocatorJoinMessage) {
      response = informAboutRemoteLocators((LocatorJoinMessage) request);
    } else if (request instanceof RemoteLocatorPingRequest) {
      response = getPingResponse((RemoteLocatorPingRequest) request);
    } else if (request instanceof RemoteLocatorRequest) {
      response = getRemoteLocators((RemoteLocatorRequest) request);
    }

    return response;
  }
When the new locator is added to remote locator metadata, inform all other locators in remote
locator metadata about the new locator so that they can update their remote locator metadata.

@param distributedSystemId Id of the joining locator.
@param locator Id of the joining locator.
@param sourceLocator Id of the locator that notified this locator about the new one.
geode-wan/src/main/java/org/apache/geode/cache/wan/internal/client/locator/LocatorMembershipListenerImpl.java