code: private void mark() throws IOException {
          if (streamState == StreamStates.OPEN) {
              if (stream.markSupported()) {
                  stream.mark(Integer.MAX_VALUE);
              } else {
                  // In case a inputStream (e.g., fileInputStream) doesn't support
                  // mark, throw a exception
                  throw new IOException("Input stream doesn't support mark");
              }
          }
      }
docs: Save the stream position, for later use with {@link #reset()}.
  
  All {@link GVRAndroidResource} streams support
  {@link InputStream#mark(int) mark()} and {@link InputStream#reset()
  reset().} Calling {@link #mark()} right after construction will allow you
  to read the header then {@linkplain #reset() rewind the stream} if you
  can't handle the file format.
  @throws IOException
  
  @since 1.6.7