private static void setReadNestedColumnPathConf(
    Configuration conf,
    String nestedColumnPaths) {
    nestedColumnPaths = nestedColumnPaths.toLowerCase();
    if (nestedColumnPaths.trim().isEmpty()) {
      conf.set(READ_NESTED_COLUMN_PATH_CONF_STR, READ_NESTED_COLUMN_PATH_CONF_STR_DEFAULT);
    } else {
      conf.set(READ_NESTED_COLUMN_PATH_CONF_STR, nestedColumnPaths);
    }
  }
Returns an array of column ids(start from zero) which is set in the given
parameter <pre>conf</pre>.
serde/src/java/org/apache/hadoop/hive/serde2/ColumnProjectionUtils.java