Unable to find any child-parent relationship for the child type about fastcrud HOT 3 CLOSED

public class Parent {
    public long Key { get; set; }
    public IEnumerable<Child> Children { get; set; }
}

public class Child {
    public long Key { get; set; }
    public long ParentKey { get; set; }
    public Parent Parent { get; set; }
}

public class Config {
    private static void ConfigureParentsAndChildren() {
        OrmConfiguration.GetDefaultEntityMapping<Parent>()
            .SetDialect(SqlDialect.MySql)
            .SetTableName("parents")

            .SetProperty(p => p.Key, p => p
                .SetDatabaseColumnName("parent_id")
                .SetPrimaryKey()
                .SetDatabaseGenerated(DatabaseGeneratedOption.Identity))

            .SetParentChildrenRelationship(                         //<-------- FAILS
                p => p.Children,
                c => c.Parent
            );

        OrmConfiguration.GetDefaultEntityMapping<Child>()
            .SetDialect(SqlDialect.MySql)
            .SetTableName("children")

            .SetProperty(p => p.Key, p => p
                .SetDatabaseColumnName("child_id")
                .SetPrimaryKey()
                .SetDatabaseGenerated(DatabaseGeneratedOption.Identity))

            .SetChildParentRelationship(
                c => c.Parent,
                c => c.ParentKey
            );
    }
}