I know it is still in early development, but with the gradle-plugin version 1.0.0 Google introduced a new compiler Jack. Using this breaks the apt plugin because the task compileJava does not exist. Also in the documentation, here, Google states that the new Jack compiler does not support annotation processing.
As long as the javac compiler can still be used this won't be an issue. But i can imagine Google will start gently forcing the Jack compiler onto developers at some point.
Will it be possible to add support for this compiler in the future?