@Override
    public String toString() {
      return "LeafNode{" +
          "keyName='" + keyName + '\'' +
          ", operator='" + operator + '\'' +
          ", value=" + value +
          (isReverseOrder ? ", isReverseOrder=true" : "") +
          '}';
    }
Constant expression side of the operator. Can currently be a String or a Long.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/parser/ExpressionTree.java