code: public Observable<Page<ResourceMetricDefinitionInner>> listMetricDefintionsAsync(final String resourceGroupName, final String name) {
          return listMetricDefintionsWithServiceResponseAsync(resourceGroupName, name)
              .map(new Func1<ServiceResponse<Page<ResourceMetricDefinitionInner>>, Page<ResourceMetricDefinitionInner>>() {
                  @Override
                  public Page<ResourceMetricDefinitionInner> call(ServiceResponse<Page<ResourceMetricDefinitionInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Get metrics that can be queried for an App Service plan, and their definitions.
  Get metrics that can be queried for an App Service plan, and their definitions.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param name Name of the App Service plan.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ResourceMetricDefinitionInner&gt; object