### Question:
MixableBase implements Mixable<SelfType> { @Override public <MixinType> SelfType with(MixinType mixinInstance) { return with(mixinInstance.getClass(), mixinInstance); }  @Override SelfType with(MixinType mixinInstance); @Override SelfType with(Class clazz, M mixinInstance); @Override M as(Class<M> clazz); @Override boolean is(Class mixinClass);  }### Answer:
@Test(expected = IllegalStateException.class) public void onlyOneMixinInstancePerTypeAllowed() { MixedClass mixedClass = new MixedClass(); mixedClass.with(TestMixin.class, new TestMixin()); mixedClass.with(TestMixin.class, new TestMixin()); }