void setUserMap(int fileId, @NotNull KeyFMap map) {
      int index = objectOffsetInSegment(fileId);
      Object oldMap = objectFieldsArray.getAndSet(index, map);
      if (oldMap == null) {
        //Entry in the objectFieldsArray must be initialized first in .initFileData(), during
        // VirtualFile lookup -- only after that VirtualFile could be made publicly available,
        // and this method is available to call. This seems to be violated:
        throw new IllegalStateException("file[#" + fileId + "]: cache record wasn't initialized yet, but already used (set " + map + ")");
      }
    }
void setUserMap(int fileId, @NotNull KeyFMap map)