@Override
    public String getCastTypeNameForCode(int code) {
        if (code == Types.VARCHAR) {
            return "varchar(256)";
        } else {
            return super.getCastTypeNameForCode(code);
        }
    }
{@code FirebirdTemplates} is an SQL dialect for Firebird
querydsl-sql/src/main/java/com/querydsl/sql/FirebirdTemplates.java