@Override
    public Object errorNode(TokenStream input, Token start, Token stop, RecognitionException e) {
      return new ASTErrorNode(input, start, stop, e);
    }
Creates an ASTNode for the given token. The ASTNode is a wrapper around
antlr's CommonTree class that implements the Node interface.

@param payload The token.
@return Object (which is actually an ASTNode) for the token.
parser/src/test/org/apache/hadoop/hive/ql/parse/HqlParser.java