Thanks, I converted my id to:

@GeneratedValue(strategy = GenerationType.IDENTITY)

but still Hibernate create the hibernate_sequence table. Even If I remove the table later, with the property spring.jpa.hibernate.ddl-auto:validate the application fails to start because Hibernate says that the hibernate_sequence table is missing.
I see in logs the creation of the table:

10/04/2018 10:02:51,578 DEBUG localhost-startStop-1 SQL: - create table `hibernate_sequence` (`next_val` bigint) engine=InnoDB
10/04/2018 10:02:51,658 DEBUG localhost-startStop-1 SQL: - insert into `hibernate_sequence` values ( 1 )

Unfortunately even with DEBUG logs activated I don't see which entity is triggering the creation of this table (not mine I guess at this point). Probably this is not the right place to write though, so I'll write on StackOverflow.