HHH-3771 - Best practice for equals implementation

Author: vladmihalcea

documentation/src/main/asciidoc/userguide/chapters/domain/entity.adoc

@@ -257,6 +257,14 @@ include::{sourcedir}/entity/listing9.java[]
 
 As you can see the question of equals/hashCode is not trivial, nor is there a one-size-fits-all solution.
 
+[TIP]
+====
+Although using a natural-id is best for `equals` and `hashCode`, sometimes you only have the entity identifier that provides a unique constraint.
+
+It's possible to use the entity identifier for equality check, but it needs a workaround.
+Check out https://vladmihalcea.com/2016/06/06/how-to-implement-equals-and-hashcode-using-the-entity-identifier/[this article for more details about the best way of mapping `equals` and `hashCode` using the entity identifier].
+====
+
 For details on mapping the identifier, see the <<chapters/domain/identifiers.adoc#identifiers,Identifiers>> chapter.
 
 [[entity-pojo-optlock]]