Applying jetty plugin Results in Namespace clash on the task "war"

I have a gradle (2.2) project doing an ant.importBuild of an ant build.xml that contains a target name=“war”. The gradle script runs fine but if I add to it the line “apply plugin: ‘jetty’” then the command “gradle tasks” results in a namespace clash on the war task. I thought the jetty plugin merely decorated the existing war task. Any ideas?

* What went wrong:
A problem occurred evaluating root project 'xyz'.
> Failed to apply plugin [id 'jetty']
   > Cannot add task ':war' as a task with that name already exists.

You’ll need to rename the Ant task on import.

I guess so, thanks.