code: public void deleteAll(List<String> keys) {
  		if (keys == null || keys.isEmpty()) {
  			return;
  		}
  		final int size = this.chunkSize;
  		IntStream.range(0, getNumChunks(keys, size))
  			.mapToObj(i -> (List<String>) partitionList(keys, i, size))
  			.forEach(chunk -> {
  				MultivaluedMap<String, String> ids = new MultivaluedHashMap<>();
  				ids.put("ids", chunk);
  				invokeDelete("_batch", ids);
  			});
  	}
docs: Deletes multiple objects.
  @param keys the ids of the objects to delete