Update samples to use new generator mappings

Closes gh-7612

spring-boot-samples/spring-boot-sample-flyway/src/main/java/sample/flyway/Person.java

@@ -19,11 +19,13 @@ package sample.flyway;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
+import javax.persistence.SequenceGenerator;
 
 @Entity
 public class Person {
 	@Id
-	@GeneratedValue
+	@SequenceGenerator(name="person_generator", sequenceName="person_sequence", allocationSize = 1)
+	@GeneratedValue(generator = "person_generator")
 	private Long id;
 	private String firstName;
 	private String lastName;

spring-boot-samples/spring-boot-sample-flyway/src/main/resources/db/migration/V1__init.sql

@@ -4,4 +4,6 @@ CREATE TABLE PERSON (
 	last_name varchar(255) not null
 );
 
+create sequence person_sequence start with 1 increment by 1;
+
 insert into PERSON (first_name, last_name) values ('Dave', 'Syer');