GCE discovery with ES 1.7

[skauk]

I need to setup a cluster for a legacy system which requires version 1.7 on GCE. I've setup two instances and installed the GCE discovery plugin according to docs (https://github.com/elastic/elasticsearch-cloud-gce/tree/v2.7.0/#version-270-for-elasticsearch-17) but they don't see each other.
All I see in logs (set to TRACE) is this:

[2018-01-12 14:06:42,696][TRACE][discovery.gce ] [Gravity] starting to ping
[2018-01-12 14:06:45,697][TRACE][discovery.gce ] [Gravity] full ping responses: {none}
[2018-01-12 14:06:45,697][DEBUG][discovery.gce ] [Gravity] filtered ping responses: (filter_client[true], filter_data[false]) {none}

Any suggestions on what could be wrong?

[skauk]

The solution to the problem was using earlier version of the plugin. Versions above 2.5 don't work.
Hope it will be useful for someone else.