IGNITE-3407 HTTP REST: query commands without pageSize failed with NPE

[Saikat Maitra]

Hi,

I have raised PR[1] for the following jira ticket[2].

Please review and let me know if any changes required.

Regards,
Saikat

[1] https://github.com/apache/ignite/pull/927
[2] https://issues.apache.org/jira/browse/IGNITE-3407