code: public BatchResult addBatch(ApplicationDefinition appDef, String shardName, OlapBatch batch) {
          return addBatch(appDef, shardName, batch, null);
      }
docs: Add a batch of updates for the given application to the given shard. Objects can
  new, updated, or deleted.
  
  @param appDef    {@link ApplicationDefinition} of application to update.
  @param shardName Shard to add batch to.
  @param batch     {@link OlapBatch} containing object updates.
  @return          {@link BatchResult} indicating results of update.