GWT Facet and Gradle build

We have a Gradle build that includes GWT code (using the de.esoco.gwt Gradle plugin).

When the project is imported, everything works fine, but in the project settings for the WAR file, the GWT module has no value for 'Target Web Facet', so Super Dev Mode is missing resources. Adding the facet manually to the project settings manually fixes the problem, but I then get a warning: 

Facet 'GWT' is imported from Gradle. Any changes made in its configuration might be lost after reimporting.

It would be nice if this was set correctly when importing the Gradle build, but I can't find any documentation that describes the settings needed in the build to make this happen. Does anyone have any information / pointer to the relevant docs?

Thanks in advance!