[TriJug] Generics Help

Anyone know the answer?
   
  Given the following code:
   
  A base class:
     class C0 {...}
   
  2 subclasses:
      class C1 extends C0 {...}
      class C2 extends C0 {...}
   
  A generic container to hold either:
      class Cont<T extends C0> {
          void add(T t) {...}
      }
   
  2 specialized containers:
      class D1 extends Cont<C1> {...}
      class D2 extends Cont<C2> {...}
   
  *Crucially now* a static method returns the matching container:
      static Cont getCont(C0 c) {
          if (c instanceof C1)  return new D1();
          if (c instanceof C2)  return new D2();
      }
   
  Expected usage:
      C0 c = new C1();  //or C2
      getCont(c).add(c);
   
  But compiles with the warning:
      Type safety: The method add(C0) belongs to the raw type Cont. References to generic type Cont<T> should be parameterized.
   
  The above is obviously contrived and there are probably other implementations that can get around the warning.  I could also suppress the warning.
   
  BUT as a learning exercise, I really want to know if there is any change that could be made to the signatures of the classes, the static method or the usage that would eliminate the warning.
   
  -Chris

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