AuthorAddressEmbeddable.java

@Entity
public class Author {

	@ElementCollection
	@MapKeyColumn(name = "address_type")
	@MapKeyEnumerated(EnumType.STRING)
	private Map<AddressType, Address>address = new HashMap<AddressType, Address>();

	...
}

AuthorBookGroup.java

@Entity
public class Author {
  
	@ManyToMany
	@JoinTable(
		      name="AuthorBookGroup",
		      joinColumns={@JoinColumn(name="fk_author", referencedColumnName="id")},
		      inverseJoinColumns={@JoinColumn(name="fk_group", referencedColumnName="id")})
	@MapKey(name = "title")
	private Map<String, BookGroup> bookGroups = new HashMap<String, BookGroup>();
  
  	...
}

BookGroup.java

@Entity
public class BookGroup {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "id", updatable = false, nullable = false)
	private Long id;
	
	@OneToMany(mappedBy = "group")
	private List<Book> books = new ArrayList<Book>();
  
	private String title;
  
	...
}

PersistSimpleAuthorBookMapping.java

Author a = new Author();
a.setFirstName("Thorben");
a.setLastName("Janssen");
em.persist(a);

Book b = new Book();
b.setTitle("Hibernate Tips");
b.setFormat(Format.PAPERBACK);
b.getAuthors().add(a);
em.persist(b);

a.getBooks().put(b.getTitle(), b);

SimpleAuthorBookMappingJoin.java

TypedQuery<Author> q = em.createQuery("SELECT a FROM Author a JOIN a.books b WHERE b.title LIKE :title", Author.class);
q.setParameter("title", "%Hibernate Tips%");
a = q.getSingleResult();

SimpleAuthorBookMappingKey.java

TypedQuery<Author> q = em.createQuery("SELECT a FROM Author a JOIN a.books b WHERE KEY(b) LIKE :title ", Author.class);
q.setParameter("title", "%Hibernate Tips%");
a = q.getSingleResult();

SimpleAuthorBookMappingList.java

@Entity
public class Author {

	@ManyToMany
	@JoinTable(
		name="BookAuthor",
		joinColumns={@JoinColumn(name="bookId", referencedColumnName="id")},
		inverseJoinColumns={@JoinColumn(name="authorId", referencedColumnName="id")})
	private List<Book> books = new ArrayList<Book>();

	...
}

SimpleAuthorBookMappingMap.java

@Entity
public class Author {

	@ManyToMany
	@JoinTable(
		name="AuthorBookGroup",
		joinColumns={@JoinColumn(name="fk_author", referencedColumnName="id")},
		inverseJoinColumns={@JoinColumn(name="fk_group", referencedColumnName="id")})
	@MapKey(name = "title")
	private Map<String, Book> books = new HashMap<String, Book>();

	...
}

Hello! Could you help me ,I found entity structure here https://www.thoughts-on-java.org/map-association-java-util-map/ but where can I find structure of database tables ?