docs: private String getFileName(int type, String tokenFilename) {
          StringBuilder sb = new StringBuilder();
          String filename = tokenFilename.substring(0, tokenFilename.indexOf(EXT_SEPERATOR));
          String ext = tokenFilename.substring(tokenFilename.indexOf(EXT_SEPERATOR));
          sb.append(filename);
          switch (type) {
              case 1:
                  sb.append(IMAGE_WATERMARK_SUFFIX);
                  break;
              case 2:
                  sb.append(IMAGE_THUMB_SUFFIX);
                  break;
          }
          sb.append(ext);
          return sb.toString();
      }