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/association/LazyUser.java

@@ -0,0 +1,50 @@
+package com.ankurm.hibernatedemo.association;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToOne;
+import jakarta.persistence.Table;
+
+/**
+ * Non-owning ("mappedBy") side of an optional {@code @OneToOne}. Docs: 12-association-mappings.md,
+ * chapter "The @OneToOne lazy trap". Even though {@link #profile} is declared
+ * {@code FetchType.LAZY}, Hibernate cannot build a proxy for it here without bytecode
+ * enhancement: it does not hold the foreign key, so it cannot know whether a profile row
+ * exists without querying. The result is an eager extra SELECT on every load of LazyUser.
+ */
+@Entity
+@Table(name = "lazy_user")
+public class LazyUser {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    private String username;
+
+    @OneToOne(mappedBy = "user", fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = true)
+    private LazyProfile profile;
+
+    protected LazyUser() {
+    }
+
+    public LazyUser(String username) {
+        this.username = username;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public LazyProfile getProfile() {
+        return profile;
+    }
+
+    public void setProfile(LazyProfile profile) {
+        this.profile = profile;
+    }
+}