@Override
  public void checkOutputSpecs(JobContext context) throws IOException, InterruptedException {
    for (String alias : getOutputFormatAliases(context)) {
      LOGGER.debug("Calling checkOutputSpecs for alias: " + alias);
      JobContext aliasContext = getJobContext(alias, context);
      OutputFormat<?, ?> outputFormat = getOutputFormatInstance(aliasContext);
      outputFormat.checkOutputSpecs(aliasContext);
      // Copy credentials and any new config added back to JobContext
      context.getCredentials().addAll(aliasContext.getCredentials());
      setAliasConf(alias, context, aliasContext);
    }
  }
Write the output key and value using the OutputFormat defined by the
alias.

@param alias the name given to the OutputFormat configuration
@param key the output key to be written
@param value the output value to be written
@param context the Mapper or Reducer Context
@throws IOException
@throws InterruptedException
hcatalog/core/src/main/java/org/apache/hive/hcatalog/mapreduce/MultiOutputFormat.java