code: public ExtensionInner get(String resourceGroupName, String clusterName, String extensionName) {
          return getWithServiceResponseAsync(resourceGroupName, clusterName, extensionName).toBlocking().single().body();
      }
docs: Gets the extension properties for the specified HDInsight cluster extension.
  
  @param resourceGroupName The name of the resource group.
  @param clusterName The name of the cluster.
  @param extensionName The name of the cluster extension.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorResponseException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the ExtensionInner object if successful.