code: public static YarnHighAvailabilityServices forSingleJobAppMaster(
  			Configuration flinkConfig,
  			org.apache.hadoop.conf.Configuration hadoopConfig) throws IOException {
  
  		checkNotNull(flinkConfig, "flinkConfig");
  		checkNotNull(hadoopConfig, "hadoopConfig");
  
  		final HighAvailabilityMode mode = HighAvailabilityMode.fromConfig(flinkConfig);
  		switch (mode) {
  			case NONE:
  				return new YarnIntraNonHaMasterServices(flinkConfig, hadoopConfig);
  
  			case ZOOKEEPER:
  				throw  new UnsupportedOperationException("to be implemented");
  
  			default:
  				throw new IllegalConfigurationException("Unrecognized high availability mode: " + mode);
  		}
  	}
docs: Creates the high-availability services for a single-job Flink YARN application, to be
  used in the Application Master that runs both ResourceManager and JobManager.
  
  @param flinkConfig  The Flink configuration.
  @param hadoopConfig The Hadoop configuration for the YARN cluster.
  
  @return The created high-availability services.
  
  @throws IOException Thrown, if the high-availability services could not be initialized.