docs: @Override
      @SuppressWarnings("unchecked")
      public void processMessage() {
          /**
           * This method in reality just delegates training to specific TrainingDriver, based on message opType.
           * In this case - SkipGram training
           */
          //log.info("sI_{} starts SkipGram round...", transport.getShardIndex());
  
          // FIXME: we might use something better then unchecked opType cast here
          TrainingDriver<SkipGramRequestMessage> sgt = (TrainingDriver<SkipGramRequestMessage>) trainer;
          sgt.startTraining(this);
      }