Snapshot created using raintank does not show custom panel plugin

When I took snapshot of grafana dashboard using option “Publish to snapshot.raintank.io” and open the generated link in another tab it does not show custom panel plugin. Snapshot shows error “Panel plugin not found: panel-id”

I was refering to below link but did find which small steps i need to perform.

It says :
However, if you are building a custom panel plugin then this will not work straight out of the box. You will need to make some small (and easy!) changes first.

What steps i need to do have custom panel plugin working in snapshot?

Thanks in advance
Grafana version 7.0.3