public static String camelCaseToConstant(String fieldName) {
    if (fieldName == null || fieldName.isEmpty()) {
      return "";
    }
    StringBuilder b = new StringBuilder();
    b.append(Character.toUpperCase(fieldName.charAt(0)));
    for (int i = 1; i < fieldName.length(); i++) {
      char c = fieldName.charAt(i);
      if (Character.isUpperCase(c)) {
        b.append('_');
      }
      b.append(Character.toUpperCase(c));
    }
    return b.toString();
  }
public static String camelCaseToConstant(String fieldName)