@Override
    public Builder startAnd() {
      ExpressionTree node = new ExpressionTree(ExpressionTree.Operator.AND);
      currentTree.getFirst().getChildren().add(node);
      currentTree.addFirst(node);
      return this;
    }
Generate the backwards compatible string for test cases
@return the sarg using the old string
storage-api/src/java/org/apache/hadoop/hive/ql/io/sarg/SearchArgumentImpl.java