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