#vulnerable code 
                                protected void callOnError(final ExecutionError error) {
        if (onError != null) {
            onError.call(error);
        }

        synchronized (error.getContext()) {
            callOnTerminate((C) error.getContext());
            error.getContext().notifyAll();
        }
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                protected void callOnError(final ExecutionError error) {
        if (onError != null) {
            onError.call(error);
        }
        callOnTerminate((C) error.getContext());
    }