code: public static org.apache.hadoop.conf.Configuration mergeAlluxioConfiguration(
        org.apache.hadoop.conf.Configuration source, AlluxioConfiguration alluxioConf) {
      org.apache.hadoop.conf.Configuration mergedConf = new org.apache.hadoop.conf.Configuration();
      source.forEach((Map.Entry<String, String> e) -> mergedConf.set(e.getKey(), e.getValue()));
      alluxioConf.copyProperties().forEach((PropertyKey pk, String val) -> {
        if (val != null) {
          mergedConf.set(pk.getName(), val);
        }
      });
      return mergedConf;
    }
docs: Merges an {@link AlluxioConfiguration} into an hadoop
  {@link org.apache.hadoop.conf.Configuration}.
  
  @param source The source hadoop configuration
  @param alluxioConf the alluxio configuration to merge
  @return a hadoop configuration object with the properties from the {@link AlluxioConfiguration}