It seems that gradle 2.14 (REL_2.14-20160504000015+0000) introduced breaking change for jacoco plugin:
In groovy version there was just dynamic property call, so JavaForkOptions was not required to be of type Task. In java version it would be more user-friendly either to change argument type to task or retrieve name property via reflection.
Thanks for the feedback, very much appreciated!
In practice, the Groovy method expected a Task that implements JavaForkOptions.
Not only the name property but also the doFirst method of Task are involved in the method body.
This commit should fix the issue by better reflecting the reality of what the method expects: https://github.com/gradle/gradle/commit/ac04fe7ffb44102b744dfcf49c53cab547e57fa2
Could you please confirm it fixes the issue for you?