code: public Observable<PublicIPAddressInner> getByResourceGroupAsync(String resourceGroupName, String publicIpAddressName, String expand) {
          return getByResourceGroupWithServiceResponseAsync(resourceGroupName, publicIpAddressName, expand).map(new Func1<ServiceResponse<PublicIPAddressInner>, PublicIPAddressInner>() {
              @Override
              public PublicIPAddressInner call(ServiceResponse<PublicIPAddressInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets the specified public IP address in a specified resource group.
  
  @param resourceGroupName The name of the resource group.
  @param publicIpAddressName The name of the subnet.
  @param expand Expands referenced resources.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PublicIPAddressInner object