public void addDefaultValueTranslation(ASTNode exprNode, String defaultValue) {
    if (!(exprNode.getType() == HiveParser.TOK_TABLE_OR_COL
            && exprNode.getChild(0).getType() == HiveParser.TOK_DEFAULT_VALUE)) {
      return;
    }

    if (defaultValue == null) {
      defaultValue = "NULL";
    }
    addTranslation(exprNode, defaultValue);
  }
Register a translation for an identifier.

@param identifier
         source node (which must be an identifier) to be replaced
ql/src/java/org/apache/hadoop/hive/ql/parse/UnparseTranslator.java