core/src/main/java/com/twitter/elephantbird/mapred/output/DeprecatedOutputFormatWrapper.java
public static void setOutputFormat(Class<?> realOutputFormatClass, Configuration conf) {
    conf.setClass("mapred.output.format.class", DeprecatedOutputFormatWrapper.class, org.apache.hadoop.mapred.OutputFormat.class);
    HadoopUtils.setClassConf(conf, CLASS_CONF_KEY, realOutputFormatClass);
  }
public static void setOutputFormat(Class<?> realOutputFormatClass, Configuration conf) {
    conf.setClass("mapred.output.format.class", DeprecatedOutputFormatWrapper.class, org.apache.hadoop.mapred.OutputFormat.class);
    HadoopUtils.setClassConf(conf, CLASS_CONF_KEY, realOutputFormatClass);
  }
For cases where we need to set hadoop1 output format in a hadoop2 Configuration object.