Describe the bug

Boolean values in WHERE clause are identified as columns rather than being identified as primitive values like numbers.

To Reproduce

Steps to reproduce the behavior:

1. Example SQL

SELECT * FROM tableA WHERE true

2. Parsing this SQL using JSqlParser with this statements

    public static void main(String[] args) throws JSQLParserException {
        Select sel = (Select) CCJSqlParserUtil.parse("SELECT * FROM tableA WHERE true");
        PlainSelect plainSelect = (PlainSelect) sel.getSelectBody();
        System.out.println(plainSelect.getWhere() instanceof Column);
    }

Expected behavior

Prints false as true in the WHERE clause is not supposed to be considered as a column name.

Actual behavior

Prints true.

System

• Database you are using: PostgreSQL
• Java Version: 11.0.3
• JSqlParser version: 3.1