### Question:
AbstractInstanceManager { public V registerMultiple( final K parent, final Selector selector, final V instance ) { if (!this.prototypes.containsKey(parent)) { this.prototypes.put(parent, new ConcurrentHashMap<>()); } return this.prototypes.get(parent).put(selector, instance); }  V registerSingle(final K parent, final V instance); V registerMultiple(
        final K parent,
        final Selector selector,
        final V instance
    ); Option<V> getMultiple(final K parent, final Selector selector); List<V> getAll(final K parent); List<V> getMultiples(final K parent); Option<V> getSingle(final K parent);  }### Answer:
@Test public void registerMultiple() { this.instanceManager.registerMultiple(PARENT, SEL_1, ACTUAL_1); this.instanceManager.registerMultiple(PARENT, SEL_2, ACTUAL_2); assertThat(this.instanceManager.getMultiple(PARENT, SEL_1).get()).isEqualTo(ACTUAL_1); assertThat(this.instanceManager.getMultiple(PARENT, SEL_2).get()).isEqualTo(ACTUAL_2); }