How to set custom URL Scheme for Development?

I want to add a feature to my plugin to make it perform an action when using a jetbrains://myProtocol/foobar link. I already added and registered a JBProtocolCommand. But I do not see a way to test it- every jetbrains:// link will be handled by Toolbox and sent to a different IDE instance than the sandbox one I am debugging my plugin in. I always get this line of log:

WARN - #c.i.o.a.Application - No URL bundle (CFBundleURLTypes) is defined in the main bundle.
To be able to open external links, specify protocols in the app layout section of the build file.
Example: args.urlSchemes = ["your-protocol"] will handle following links: your-protocol://open?file=file&line=line

How to “specify protocols in the app layout section of the build file”? I guess there must be some way to configure it to be “jetbrains-myplugin://” or whatever to make sure only the sandbox IDE instance picks it up.

I am using the org.jetbrains.intellij Gradle plugin.