presto-main/src/main/java/io/prestosql/operator/HttpPageBufferClient.java/HttpPageBufferClient/toString
class HttpPageBufferClient:        @Override
        public String toString()
        {
            return toStringHelper(this)
                    .add("token", token)
                    .add("nextToken", nextToken)
                    .add("pagesSize", pages.size())
                    .add("clientComplete", clientComplete)
                    .toString();
        }