code: public Observable<InterfaceEndpointInner> getByResourceGroupAsync(String resourceGroupName, String interfaceEndpointName, String expand) {
          return getByResourceGroupWithServiceResponseAsync(resourceGroupName, interfaceEndpointName, expand).map(new Func1<ServiceResponse<InterfaceEndpointInner>, InterfaceEndpointInner>() {
              @Override
              public InterfaceEndpointInner call(ServiceResponse<InterfaceEndpointInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets the specified interface endpoint by resource group.
  
  @param resourceGroupName The name of the resource group.
  @param interfaceEndpointName The name of the interface endpoint.
  @param expand Expands referenced resources.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the InterfaceEndpointInner object