CircularReference.java

import java.util.function.Supplier;

public enum CircularReference {
	P1(() -> Child.C1),
	P2(() -> Child.C2);

	public enum Child {
		C1(P1),
		C2(P2);

		private final CircularReference parent;

		private Child(CircularReference parent) {
			this.parent = parent;
		}

		public CircularReference getParent() {
			return parent;
		}
	}

	private final Supplier<Child> supplier;

	private CircularReference(Supplier<Child> supplier) {
		this.supplier = supplier;
	}

	public Child getChild() {
		return supplier.get();
	}
}