public CompoundConfiguration add(final Configuration conf) {
    freezeMutableConf();

    if (conf instanceof CompoundConfiguration) {
      this.configs.addAll(0, ((CompoundConfiguration) conf).configs);
      return this;
    }
    // put new config at the front of the list (top priority)
    this.configs.add(0, new ImmutableConfWrapper(conf));
    return this;
  }
Add Hadoop Configuration object to config list. The added configuration overrides the previous
ones if there are name collisions.
@param conf configuration object
@return this, for builder pattern
hbase-common/src/main/java/org/apache/hadoop/hbase/CompoundConfiguration.java