@Override
    public Builder literal(TruthValue truth) {
      ExpressionTree parent = currentTree.getFirst();
      parent.getChildren().add(new ExpressionTree(truth));
      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