Update samples to use new generator mappings

Closes gh-7612

spring-boot-samples/spring-boot-sample-data-jpa/src/main/java/sample/data/jpa/domain/City.java

@@ -22,6 +22,7 @@ import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
+import javax.persistence.SequenceGenerator;
 
 @Entity
 public class City implements Serializable {
@@ -29,7 +30,8 @@ public class City implements Serializable {
 	private static final long serialVersionUID = 1L;
 
 	@Id
-	@GeneratedValue
+	@SequenceGenerator(name="city_generator", sequenceName="city_sequence", initialValue = 23)
+	@GeneratedValue(generator = "city_generator")
 	private Long id;
 
 	@Column(nullable = false)

spring-boot-samples/spring-boot-sample-data-jpa/src/main/java/sample/data/jpa/domain/Hotel.java

@@ -26,6 +26,7 @@ import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
 import javax.persistence.ManyToOne;
 import javax.persistence.OneToMany;
+import javax.persistence.SequenceGenerator;
 
 import org.hibernate.annotations.NaturalId;
 
@@ -35,7 +36,8 @@ public class Hotel implements Serializable {
 	private static final long serialVersionUID = 1L;
 
 	@Id
-	@GeneratedValue
+	@SequenceGenerator(name="hotel_generator", sequenceName="hotel_sequence", initialValue = 28)
+	@GeneratedValue(generator = "hotel_generator")
 	private Long id;
 
 	@ManyToOne(optional = false)

spring-boot-samples/spring-boot-sample-data-jpa/src/main/java/sample/data/jpa/domain/Review.java

@@ -26,6 +26,7 @@ import javax.persistence.Enumerated;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
 import javax.persistence.ManyToOne;
+import javax.persistence.SequenceGenerator;
 import javax.persistence.Temporal;
 import javax.persistence.TemporalType;
 
@@ -37,7 +38,8 @@ public class Review implements Serializable {
 	private static final long serialVersionUID = 1L;
 
 	@Id
-	@GeneratedValue
+	@SequenceGenerator(name="review_generator", sequenceName="review_sequence", initialValue = 64)
+	@GeneratedValue(generator = "review_generator")
 	private Long id;
 
 	@ManyToOne(optional = false)