code: public <T extends InteractionAwareFixture> T create(Class<T> clazz, int constructorArg) {
          return create(clazz, new Class<?>[] {int.class}, new Object[] {constructorArg});
      }
docs: Creates new instance of fixture.
  @param clazz class to instantiate.
  @param constructorArg argument to pass to constructor of clazz.
  @param <T> type to create.
  @return instance of clazz (subclass, actually) that will have #aroundSlimInvoke() invoked on each method call.