### Question:
AttributeKey implements Serializable { public AttributeKey<T> instance(String instanceId) { return new AttributeKey<T>(NamespacedKey.representation(this.namespace, this.id, instanceId), type); } AttributeKey(String name, Type type); static AttributeKey<T> create(String name, Class<T> simpleType); static AttributeKey<Set<T>> createSetOf(String name, Class<T> containedType); static AttributeKey<List<T>> createListOf(String name, Class<T> containedType); static AttributeKey<Map<String, T>> createMapOf(String name, Class<T> containedType); static AttributeKey<?> createType(String name, Type complexType); String getName(); Type getType(); String getNamespace(); String getId(); @Nullable String getInstance(); boolean isInstance(); AttributeKey<T> instance(String instanceId); AttributeValue<T> valueOf(final T value); AttributeValue<T> coerceToValue(Object value); @Override String toString(); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test public void testInstance() throws Exception { AttributeKey<String> key = AttributeKey.create("namespace:id:instance", String.class); assertEquals("namespace:id:instance", key.getName()); assertEquals("namespace", key.getNamespace()); assertEquals("id", key.getId()); assertTrue(key.isInstance()); assertEquals("instance", key.getInstance()); }