private String targetCaseOrNull(String text) {
        if (targetCase == LetterCase.LOWER) {
            return text.toLowerCase(locale);
        } else {
            return text.toUpperCase(locale);
        }
    }
Constructor.
@param targetCase The characters of all table and column names will be converted to the specified letter-case.
@param locale The locale that is used for the letter-case conversion.
querydsl-sql/src/main/java/com/querydsl/sql/namemapping/ChangeLetterCaseNameMapping.java