code: @Override
    public void trim(MemoryTrimType trimType) {
      if (!mSemaphore.tryAcquire()) {
        return;
      }
      try {
        mByteArraySoftRef.clear();
      } finally {
        mSemaphore.release();
      }
    }
docs: Responds to memory pressure by simply 'discarding' the local byte array if it is not used
  at the moment.
  
  @param trimType kind of trimming to perform (ignored)