I found strange generics behaviour. In two words - thing I realy want is to use ComplexObject1 in most general way, and the thing I realy missed is why defined generic type(... extends BuisnessObject) is lost. The discuss thread is also awailable in my blog http://pronicles.blogspot.com/2010/03/unexpected-generics-behaviour.html.

public class Test {

  public interface EntityObject {}

  public interface SomeInterface {}

  public class BasicEntity implements EntityObject {}

  public interface BuisnessObject<E extends EntityObject> {
    E getEntity();
  }

  public interface ComplexObject1<V extends SomeInterface> extends BusinessObject<BasicEntity> {}

  public interface ComplexObject2 extends BuisnessObject<BasicEntity> {}

  public void test(){
    ComplexObject1 complexObject1 = null;
    ComplexObject2 complexObject2 = null;

    EntityObject entityObject1 = complexObject1.getEntity();
    //BasicEntity entityObject1 = complexObject1.getEntity(); wtf incompatible types!!!!
    BasicEntity basicEntity = complexObject2.getEntity();
  }
}