The following code confuses java editor but compiles just fine:

---- CODE BEGIN ----
package generics.bug;

abstract class AbstractResponse { }

abstract class AbstractRequest<T extends AbstractResponse> { }

interface Handler {
    <R extends AbstractResponse, Q extends AbstractRequest<R>>
        R execute(Q request);
}

class Response extends AbstractResponse {
    private int number;

    public Response(int number) { this.number = number; }

    public int getNumber() { return number; }

}

class Request extends AbstractRequest<Response> {
    private int data;

    public Request(int data) { this.data = data; }

    public int getData() { return data; }

}
public class TestCase implements Handler {

    public static void main(String... args) {
        TestCase test = new TestCase();
        Response response = test.execute(new Request(1));
        response.getNumber(); // gets through the IDE built-in parser just fine

        // \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
        test.execute(new Request(1)).getNumber(); // DOES NOT WORK
        // shows popup with "cannot find symbol AbstractResponse.getNumber()
        // \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
    }

    public
        <R extends AbstractResponse, Q extends AbstractRequest<R>>
        R execute(Q request)
    {
        System.out.printf("execute DONE, request class %s%n",
            request.getClass().getName());
        return null;
    }

}
---- CODE END ----


Observed for 6.1 and 6.5 m1 on Windows XP, JDK 1.6.0_05:

Product Version: NetBeans IDE 6.1 (Build 200804211638)
Java: 1.6.0_05; Java HotSpot(TM) Client VM 10.0-b19
System: Windows XP version 5.1 running on x86; Cp1251; ru_RU (nb)

Product Version: NetBeans IDE Dev (Build 200807040101)
Java: 1.6.0_05; Java HotSpot(TM) Client VM 10.0-b19
System: Windows XP version 5.1 running on x86; Cp1251; ru_RU (nb)

The same code causes no issues in Eclipse 3.2 and above.

Thank you.