docs: private static String createMessage(String fieldName, Number value,
                                          Number lowerBound, Number upperBound, String explain) {
          StringBuilder buf = new StringBuilder()
              .append("Value ").append(value).append(" for ").append(fieldName).append(' ');
  
          if (lowerBound == null) {
              if (upperBound == null) {
                  buf.append("is not supported");
              } else {
                  buf.append("must not be larger than ").append(upperBound);
              }
          } else if (upperBound == null) {
              buf.append("must not be smaller than ").append(lowerBound);
          } else {
              buf.append("must be in the range [")
                  .append(lowerBound)
                  .append(',')
                  .append(upperBound)
                  .append(']');
          }
          if (explain != null) {
              buf.append(": ").append(explain);
          }
  
          return buf.toString();
      }