code: public static void getAllRecommendationFiles(final Set<String> recommendationFiles, final File path, final String prefix, final String suffix) {
          if (path == null) {
              return;
          }
          File[] files = path.listFiles();
          if (files == null) {
              return;
          }
          for (File file : files) {
              if (file.isDirectory()) {
                  getAllRecommendationFiles(recommendationFiles, file, prefix, suffix);
              } else if (file.getName().startsWith(prefix) && file.getName().endsWith(suffix)) {
                  recommendationFiles.add(file.getAbsolutePath());
              }
          }
      }
docs: Get all recommendation files.
  
  @param recommendationFiles The recommendation files (what is this?)
  @param path The path of the recommendation files.
  @param prefix The prefix of the recommendation files.
  @param suffix The suffix of the recommendation files.