code: private static void addContentsToQueue(Queue<File> fileQueue, File sourceDir) throws MojoExecutionException
      {
          File[] files = sourceDir.listFiles();
          if (files != null) {
              for (File currentFile : files) {
                  fileQueue.add(currentFile);
              }
          } else {
              throw new MojoExecutionException(String.format("Couldn't get list of files in source dir [%s]", sourceDir));
          }
      }
docs: Adds the contents of a specific directory to a queue of files.
  
  @param fileQueue the queue of files
  @param sourceDir the directory to be scanned