The following program compiles on jdk 1.5 and jdk 1.6 without error (and oddly, 
without an unchecked cast warning), but the netbeans' inline error detection 
reports an "inconvertible types":

import java.util.*;

public class Test extends ArrayList<Object> {
    public <T> ArrayList<T> test(Class<T> clazz) {
        if (clazz == Object.class) {
            // The following return encounters 2 bugs:
            // 1) Netbeans inline error detection improperly identifies it as 
            //    an "inconvertible type", even though it compiles
            // 2) The current 1.5 and 1.6 compilers compile it without giving
            //    an "unchecked cast" warning
            return (ArrayList<T>)this;
            
            // A simple workaround to get the results I expected is to use an
            // intermediate cast, as follows:
            // return (ArrayList<T>)((ArrayList<Object>)this);
        }
        // ... other junk
        return null;
    }
}