docs: public static String escapeNonAscii(String source) {
  
          if (source == null) {
              return null;
          }
          StringBuffer result = new StringBuffer(source.length() * 2);
          for (int i = 0; i < source.length(); i++) {
              int ch = source.charAt(i);
              if (ch > 255) {
                  result.append(ENTITY_PREFIX);
                  result.append(ch);
                  result.append(";");
              } else {
                  result.append((char)ch);
              }
          }
          return new String(result);
      }