docs: private boolean hasFileChangedUnexpectedly() {
          synchronized (this) {
              if (mDiskWritesInFlight > 0) {
                  // If we know we caused it, it's not unexpected.
                  if (DEBUG) System.out.println( "disk write in flight, not unexpected.");
                  return false;
              }
          }
          if (!mFile.canRead()) {
              return true;
          }
          synchronized (this) {
              return mStatTimestamp != mFile.lastModified() || mStatSize != mFile.length();
          }
      }