Merge pull request #19040 from kriti20041/javadoc-clarity-fix

Add JavaDoc explaining composite key usage in Book entity

Author: lor6

persistence-modules/spring-data-jpa-annotations/src/main/java/com/baeldung/composite/entity/Book.java

@@ -2,7 +2,11 @@
 
 import javax.persistence.EmbeddedId;
 import javax.persistence.Entity;
-
+/**
+ * JPA entity representing a Book with a composite primary key.
+ *
+ * Uses {@link BookId} as an embedded identifier.
+ */
 @Entity
 public class Book {