application with agent startup and report illegal field modifiers in class

[YK-Leung]

jdk: 1.7
skywalking: 6.6
spring: 4.0.4
Other same versions projects with agent are startup normally except this，the error in agent log:

my code :

public interface TaskCallback<T> extends ListenableFutureCallback<T> { public void onTimeout(); }

public interface ListenableTask<T> extends Callable<T>, TaskCallback<T> { }

[wu-sheng]

@ascrutae Please take a look.

[YK-Leung]

@ascrutae Please take a look.

i rewrite my interface to class and reboot success now, thank you

[leohuai]

@ascrutae Please take a look.

i rewrite my interface to class and reboot success now, thank you

how do you fix it？I met the same error