code: public Observable<HybridConnectionKeyInner> listHybridConnectionKeysAsync(String resourceGroupName, String name, String namespaceName, String relayName) {
          return listHybridConnectionKeysWithServiceResponseAsync(resourceGroupName, name, namespaceName, relayName).map(new Func1<ServiceResponse<HybridConnectionKeyInner>, HybridConnectionKeyInner>() {
              @Override
              public HybridConnectionKeyInner call(ServiceResponse<HybridConnectionKeyInner> response) {
                  return response.body();
              }
          });
      }
docs: Get the send key name and value of a Hybrid Connection.
  Get the send key name and value of a Hybrid Connection.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param name Name of the App Service plan.
  @param namespaceName The name of the Service Bus namespace.
  @param relayName The name of the Service Bus relay.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the HybridConnectionKeyInner object