I have a project using HotChocolate and EFCore where I have the following entities:
public class Entity
{
  public int EntityId { get; set; }
  public string Name { get; set; }
  public string AuthorId { get; set; }
}
public class Author
{
  public string AuthorId { get; set; }
  public string Name { get; set; }
}
There is no association between the Entity and Author tables. The Author is retrieved by a LEFT JOIN.
The Entity type is exposed in GraphQL as follows:
public class EntityDto
{
  public int EntityId { get; set; }
  public string Name { get; set; }
  public Author Author { get; set; }
}
[UseOffsetPaging, UseProjection, UseFiltering, UseSorting]
public IQueryable<EntityDto> Entities([Service] DbContext dbContext)
{
    return dbContext.Entity
      .GroupJoin(...)
      .Select(...);
}
Now, I'm willing to be able to apply the following filter criteria:
query {
  entities(where: { author: { eq: "John" } }) {
    ...
  }
}
The author filter should get applied on the AuthorId property of the Entity class.
How can I achieve that?