presto-main/src/main/java/io/prestosql/execution/buffer/BufferResult.java/BufferResult/toString
class BufferResult:    @Override
    public String toString()
    {
        return toStringHelper(this)
                .add("token", token)
                .add("nextToken", nextToken)
                .add("taskInstanceId", taskInstanceId)
                .add("bufferComplete", bufferComplete)
                .add("serializedPages", serializedPages)
                .toString();
    }