code: private String getProjectFile( String projectName, String filePattern)
      {
      String projectFile = null;
      if( !StringUtils.isBlank( filePattern))
        {
        Matcher matcher = projectFilePattern_.matcher( filePattern);
        if( matcher.matches())
          {
          projectFile =
            StringUtils.isBlank( matcher.group(2))
            ? filePattern
            : matcher.group(1) + projectName + matcher.group(3);
          }
        }
      
      return projectFile;
      }
docs: Returns the file name defined by applying the given pattern to the project name.
  Returns null if the file pattern is invalid.