code: public BeatGrid requestBeatGridFrom(final DataReference track) {
          for (BeatGrid cached : hotCache.values()) {
              if (cached.dataReference.equals(track)) {  // Found a hot cue hit, use it.
                  return cached;
              }
          }
          return requestBeatGridInternal(track, false);
      }
docs: Ask the specified player for the beat grid of the track in the specified slot with the specified rekordbox ID,
  first checking if we have a cache we can use instead.
  
  @param track uniquely identifies the track whose beat grid is desired
  
  @return the beat grid, if any