code: public <C extends Contextual<I>, I> C getContextual(String id) {
          return this.<C, I>getContextual(new StringBeanIdentifier(id));
      }
docs: Given a particular id, return the correct contextual. For contextuals
  which aren't passivation capable, the contextual can't be found in another
  container, and null will be returned.
  
  @param id An identifier for the contextual
  @return the contextual