code: public Observable<Page<ResourceMetricDefinitionInner>> listWorkerPoolInstanceMetricDefinitionsAsync(final String resourceGroupName, final String name, final String workerPoolName, final String instance) {
          return listWorkerPoolInstanceMetricDefinitionsWithServiceResponseAsync(resourceGroupName, name, workerPoolName, instance)
              .map(new Func1<ServiceResponse<Page<ResourceMetricDefinitionInner>>, Page<ResourceMetricDefinitionInner>>() {
                  @Override
                  public Page<ResourceMetricDefinitionInner> call(ServiceResponse<Page<ResourceMetricDefinitionInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Get metric definitions for a specific instance of a worker pool of an App Service Environment.
  Get metric definitions for a specific instance of a worker pool of an App Service Environment.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param name Name of the App Service Environment.
  @param workerPoolName Name of the worker pool.
  @param instance Name of the instance in the worker pool.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ResourceMetricDefinitionInner&gt; object