code: @BetaApi
    public final Operation attachNetworkEndpointsNetworkEndpointGroup(
        String networkEndpointGroup,
        NetworkEndpointGroupsAttachEndpointsRequest
            networkEndpointGroupsAttachEndpointsRequestResource) {
  
      AttachNetworkEndpointsNetworkEndpointGroupHttpRequest request =
          AttachNetworkEndpointsNetworkEndpointGroupHttpRequest.newBuilder()
              .setNetworkEndpointGroup(networkEndpointGroup)
              .setNetworkEndpointGroupsAttachEndpointsRequestResource(
                  networkEndpointGroupsAttachEndpointsRequestResource)
              .build();
      return attachNetworkEndpointsNetworkEndpointGroup(request);
    }
docs: Attach a list of network endpoints to the specified network endpoint group.
  
  <p>Sample code:
  
  <pre><code>
  try (NetworkEndpointGroupClient networkEndpointGroupClient = NetworkEndpointGroupClient.create()) {
  ProjectZoneNetworkEndpointGroupName networkEndpointGroup = ProjectZoneNetworkEndpointGroupName.of("[PROJECT]", "[ZONE]", "[NETWORK_ENDPOINT_GROUP]");
  NetworkEndpointGroupsAttachEndpointsRequest networkEndpointGroupsAttachEndpointsRequestResource = NetworkEndpointGroupsAttachEndpointsRequest.newBuilder().build();
  Operation response = networkEndpointGroupClient.attachNetworkEndpointsNetworkEndpointGroup(networkEndpointGroup.toString(), networkEndpointGroupsAttachEndpointsRequestResource);
  }
  </code></pre>
  
  @param networkEndpointGroup The name of the network endpoint group where you are attaching
  network endpoints to. It should comply with RFC1035.
  @param networkEndpointGroupsAttachEndpointsRequestResource
  @throws com.google.api.gax.rpc.ApiException if the remote call fails