public static Set<String> getNestedColumnPaths(Configuration conf) {
    String skips =
      conf.get(READ_NESTED_COLUMN_PATH_CONF_STR, READ_NESTED_COLUMN_PATH_CONF_STR_DEFAULT);
    return new HashSet<>(Arrays.asList(StringUtils.split(skips)));
  }
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