#ManyToOne mapping without an entity for the intermediate table - database

Question

I am writing an application that will query a massive Database, that cannot be changed.
For that reason, my application does not need to map all Objects, since that would be useless and time consuming.
All entities there mapped are #Immutable.
I came across this relationship:
I want to Map Order, and have it reference Customer. It is, in fact, a Many to One Relationship, it just happens two be two Join clauses away.
I am not interested in neither R nor B, since they convey no information related to my requirement.
I envision something like this, but I know the syntax is invalid:
#Entity
#Immutable
#Table(name = "Order")
public class Order implements Serializable {
#Id
#Column(name = "id")
private Long id;
#ManyToOne
#JoinColumns(value =
#JoinColumn(table = "R", name = "id", referencedColumnName = "R_id"),
#JoinColumn(table = "Customer", name = "id", referencedColumnName = "Customer_id")
)
private Customer customer;
... more data and getters/setters omitted ...
}
#Entity
#Immutable
#Table(name = "Customer")
public class Customer implements Serializable {
#Id
#Column(name = "id")
private Long id;
... more data and getters/setters omitted ...
}
Is there a way I can do this, without creating an entity for R?
EDIT: -------------------------
I tried the following, as per suggestion:
#ManyToOne
#JoinTable(name = "R",
joinColumns = #JoinColumn(name = "id", referencedColumnName = "R_id"),
inverseJoinColumns = #JoinColumn(name = "id", referencedColumnName = "Customer_id"))
private Customer customer;
However, I get the following error:
Unable to find column with logical name: R_id in org.hibernate.mapping.Table(Order) and its related supertables and secondary tables

Answer 1

You could use the #JoinTable annotation for the following schema.
in this way
#Entity
#Table(name = "Order")
public class Order {
// ...
#ManyToOne
#JoinTable(
name = "R",
joinColumns = #JoinColumn(name = "ord_id"),
inverseJoinColumns = #JoinColumn(name = "customer_id"))
private Customer customer;
// ...
}
But for your case it looks like not possible to avoid usage of entity for intermediate table R due to the lack of foreign key to the Order table in the R.