JPA Nested Element Collection

I am trying to figure out if something like this type of Element Collection nesting is possible within JPA? Or at least doing something like this that would not require me to declare a new separate Entity which would hold the inner collection. I have seen usage of @MapKeyColumn & @CollectionTable with java Maps but, am not sure this would help solve.

@Table
@Entity
public class MyClass {
   @Id
   private int myid;
   
   @ElementCollection
   private Map<String, List<String>> mymap;
}

According to the hibernate documentation:

> 2.8.2. Collections of value types
>
> Collections of value type include basic and embeddable types. Collections cannot be nested, and, when used in collections, embeddable types are not allowed to define other collections.
>
> For collections of value types, JPA 2.0 defines the @ElementCollection annotation. The lifecycle of the value-type collection is entirely controlled by its owning entity.

So, you should declare an intermediate entity to solve your problem. Below you can see a simple example.

1. The database schema:

create table MY_PATIENT
(
   PAT_RECID  number,
   PAT_NAME varchar2(100),
   
   constraint PAT_PK primary key(PAT_RECID)
);

create table MY_ORDER
(
   ORD_RECID  number,
   ORD_CODE varchar2(15),
   ORD_PATID number,
   
   constraint ORD_PK primary key(ORD_RECID),
   constraint ORD_PAT_FK foreign key(ORD_PATID) references MY_PATIENT(PAT_RECID),
   constraint ORD_CODE_UNIQUE unique (ORD_CODE)
);

create table MY_TEST
(
   TST_RECID  number,
   TST_CODE varchar2(20),
   TST_ORDID number,
   
   constraint TST_PK primary key(TST_RECID),
   constraint TST_ORD_FK foreign key(TST_ORDID) references MY_ORDER(ORD_RECID),
   constraint TST_CODE_UNIQUE unique (TST_CODE)
);

2. Appropriate hibernate mapping:

@Entity
@Table(name = "MY_PATIENT")
public class Patient
{
   @Id
   @Column(name = "PAT_RECID")
   private Long id;

   @Column(name = "PAT_NAME")
   private String name;

   @OneToMany(mappedBy = "patient")
   @MapKey(name = "code")
   private Map<String, Order> orders;
}

@Entity
@Table(name = "MY_ORDER")
public class Order
{
   @Id
   @Column(name = "ORD_RECID")
   private Long id;

   @Column(name = "ORD_CODE")
   private String code;

   @ManyToOne
   @JoinColumn(name = "ORD_PATID")
   private Patient patient;

   @ElementCollection
   @CollectionTable(name = "MY_TEST", joinColumns = {@JoinColumn(name = "TST_ORDID")})
   @Column(name = "TST_CODE")
   private List<String> tests;
}