code: public Observable<ResourceGroupInner> getAsync(String resourceGroupName) {
          return getWithServiceResponseAsync(resourceGroupName).map(new Func1<ServiceResponse<ResourceGroupInner>, ResourceGroupInner>() {
              @Override
              public ResourceGroupInner call(ServiceResponse<ResourceGroupInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets a resource group.
  
  @param resourceGroupName The name of the resource group to get. The name is case insensitive.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ResourceGroupInner object