public ConfigureHadoop withXml(ConfigFile file, String xmlPath) {
      String arg = "";

      switch (file) {
      case Site: arg = "-S"; break;
      case Default: arg = "-D"; break;
      case Core: arg = "-C"; break;
      case Hdfs: arg = "-H"; break;
      case Mapred: arg = "-M"; break;
      }

      args.add(arg);
      args.add(xmlPath);
      return this;
    }
Specify an XML file in S3 to merge with Hadoop's default configuration.
@param file The config file to merge with.
@param xmlPath The path in S3 of the XML file.
@return A reference to this updated object so that method calls can be chained
        together.
aws-java-sdk-emr/src/main/java/com/amazonaws/services/elasticmapreduce/util/BootstrapActions.java