code: public Observable<ExpressRouteLinkInner> getAsync(String resourceGroupName, String expressRoutePortName, String linkName) {
          return getWithServiceResponseAsync(resourceGroupName, expressRoutePortName, linkName).map(new Func1<ServiceResponse<ExpressRouteLinkInner>, ExpressRouteLinkInner>() {
              @Override
              public ExpressRouteLinkInner call(ServiceResponse<ExpressRouteLinkInner> response) {
                  return response.body();
              }
          });
      }
docs: Retrieves the specified ExpressRouteLink resource.
  
  @param resourceGroupName The name of the resource group.
  @param expressRoutePortName The name of the ExpressRoutePort resource.
  @param linkName The name of the ExpressRouteLink resource.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ExpressRouteLinkInner object