docs: static String concatFilePathNames(String leftPath,
                                      String rightPath,
                                      String fileSep)
    {
      String leftPathTrimmed = leftPath.trim();
      String rightPathTrimmed = rightPath.trim();
  
      if (leftPathTrimmed.isEmpty())
      {
        return rightPath;
      }
  
      if (leftPathTrimmed.endsWith(fileSep)
          && rightPathTrimmed.startsWith(fileSep))
      {
        return leftPathTrimmed + rightPathTrimmed.substring(1);
      }
      else if (!leftPathTrimmed.endsWith(fileSep)
               && !rightPathTrimmed.startsWith(fileSep))
      {
        return leftPathTrimmed + fileSep + rightPathTrimmed;
      }
      else
      {
        return leftPathTrimmed + rightPathTrimmed;
      }
    }