code: public HybridConnectionKeyInner listHybridConnectionKeys(String resourceGroupName, String name, String namespaceName, String relayName) {
          return listHybridConnectionKeysWithServiceResponseAsync(resourceGroupName, name, namespaceName, relayName).toBlocking().single().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
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the HybridConnectionKeyInner object if successful.