Add Hibernate 7 batches 2-6, batch 7, and batch 8: mapping styles, JPA annotations, natural IDs, @Immutable, stored procedures, in-memory test databases, JNDI mocking, proxies, associations, temporal mapping, named queries, HQL, Criteria API, EntityManager bootstrapping, Ehcache 3 L2 cache configuration, HikariCP connection pooling, Hibernate Validator CDI integration, aggregate functions, sorting, pagination, interceptors, and Hibernate Search 8 (Hibernate 7.4.5.Final + Spring Boot 4.1.1 + JDK 25)

src/main/java/com/ankurm/hibernatedemo/persistenceannotations/IdentityHashSetEntity.java

@@ -0,0 +1,41 @@
+package com.ankurm.hibernatedemo.persistenceannotations;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+
+/**
+ * Deliberately relies on the JPA/Hibernate DEFAULT {@code equals()}/{@code hashCode()}
+ * (identity-based, inherited from Object) with a surrogate {@code @GeneratedValue} id that is
+ * null until the first flush. This is the entity used to reproduce the classic
+ * "HashSet.contains() returns false after persist()" symptom.
+ *
+ * <p>Docs: docs/05-jpa-persistence-annotations.md, Topic 2.
+ */
+@Entity
+public class IdentityHashSetEntity {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+
+    private String label;
+
+    public IdentityHashSetEntity() {
+    }
+
+    public IdentityHashSetEntity(String label) {
+        this.label = label;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    // Deliberately NOT overriding equals()/hashCode() -- uses Object identity.
+    // A second class below overrides them using the surrogate id, to show that trap too.
+}