presto-main/src/main/java/io/prestosql/execution/buffer/OutputBuffers.java/OutputBuffers/createInitialEmptyOutputBuffers
class OutputBuffers:    public static OutputBuffers createInitialEmptyOutputBuffers(PartitioningHandle partitioningHandle)
    {
        BufferType type;
        if (partitioningHandle.equals(FIXED_BROADCAST_DISTRIBUTION)) {
            type = BROADCAST;
        }
        else if (partitioningHandle.equals(FIXED_ARBITRARY_DISTRIBUTION)) {
            type = ARBITRARY;
        }
        else {
            type = PARTITIONED;
        }
        return new OutputBuffers(type, 0, false, ImmutableMap.of());
    }