docs: public static final String isDestinationPrefixValid(String destinationPrefix)
      {
  
          String result = VALID; // Assume the prefix is valid until we know otherwise.
          boolean isValid = true;
  
          // null indicates that no destination prefix is being used.
          if (null != destinationPrefix)
          {
              // Check for the length first.
              int len = destinationPrefix.length();
  
              if (len > DESTINATION_PREFIX_MAX_LENGTH)
              {
                  isValid = false;
                  result = MAX_LENGTH_EXCEEDED;
              }
              else
              {
                  // Cycle through each character in the prefix until we find an invalid character, 
                  // or until we come to the end of the string.
                  int along = 0;
  
                  while ((along < len) && isValid)
                  {
                      char c = destinationPrefix.charAt(along);
                      if (!(('A' <= c) && ('Z' >= c)))
                      {
                          if (!(('a' <= c) && ('z' >= c)))
                          {
                              if (!(('0' <= c) && ('9' >= c)))
                              {
                                  if ('.' != c && '/' != c && '%' != c)
                                  {
                                      // This character isn't a valid one...  
                                      isValid = false;
                                      result = String.valueOf(c);
                                  }
                              }
                          }
                      }
                      // Move along to the next character in the string.
                      along += 1;
                  }
              }
          }
          return result;
      }