How does Hibernate find the generic type of a collection in a @OneToMany mapping?

Question

Given a simple entity relationship:

@Entity
public class Single {

  @OneToMany
  public Set<Multiple> multiples;
}

How does Hibernate find out that the generic type of multiples is Multiple? This information is impossible to find with the standard Reflection API.

I'm looking through the source code, but don't really know where to start.

Answer 1

But it is possible to find out using reflection API. Take a look at Field.getGenericType():

Type type = field.getGenericType();
if (type instanceof ParameterizedType) {
  Type[] genericArguments = ((ParameterizedType) type).getActualTypeArguments();
}