core/src/main/java/com/twitter/elephantbird/mapreduce/input/combine/DelegateCombineFileInputFormat.java
public static void setCombinedInputFormatDelegate(Configuration conf, Class<? extends InputFormat> clazz) {
    HadoopUtils.setClassConf(conf, COMBINED_INPUT_FORMAT_DELEGATE, clazz);
  }
public static void setCombinedInputFormatDelegate(Configuration conf, Class<? extends InputFormat> clazz) {
    HadoopUtils.setClassConf(conf, COMBINED_INPUT_FORMAT_DELEGATE, clazz);
  }
This sets configures the delegate, though it does not configure DelegateCombineFileInputFormat.