@SuppressWarnings("unchecked")
  public <T> T[] convertToArray(Map<Byte, T> source, Class<T> compType) {
    T[] result = (T[]) Array.newInstance(compType, getTagLength());
    for (Map.Entry<Byte, T> entry : source.entrySet()) {
      result[entry.getKey()] = entry.getValue();
    }
    return result;
  }
@param skewKeysValuesTables
         set the table desc for storing skew keys and their corresponding
         value;
ql/src/java/org/apache/hadoop/hive/ql/plan/JoinDesc.java