code: public Observable<ContainerGroupInner> getByResourceGroupAsync(String resourceGroupName, String containerGroupName) {
          return getByResourceGroupWithServiceResponseAsync(resourceGroupName, containerGroupName).map(new Func1<ServiceResponse<ContainerGroupInner>, ContainerGroupInner>() {
              @Override
              public ContainerGroupInner call(ServiceResponse<ContainerGroupInner> response) {
                  return response.body();
              }
          });
      }
docs: Get the properties of the specified container group.
  Gets the properties of the specified container group in the specified subscription and resource group. The operation returns the properties of each container group including containers, image registry credentials, restart policy, IP address type, OS type, state, and volumes.
  
  @param resourceGroupName The name of the resource group.
  @param containerGroupName The name of the container group.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ContainerGroupInner object