.Net 8 + NHibernate

[zdenotirc]

Hello, I have a question regarding NHibernate and .Net 8 compatibility.
We have a database with composite keys, NHibernate 5.5.2 and .Net Framework 4.8 and mapping works correctly.
When we tried to switch to .Net 8, with same Nhibernate version and same mapping, Nhibernate stops working correctly.
What could be an issue with .Net 8?
Foreign Key constrain exceptions are thrown. For example, if we have defined FK in database, this works correctly with .Net Framework 4.8

ALTER TABLE "SOME_TABLE" ADD CONSTRAINT "FC1_SOME_TABLE" FOREIGN KEY("FirstName", "SecondName") REFERENCES "SOME_PARENT_TABLE" ("FirstName", "SecondName")

idMapper.ManyToOne(
                    e => e.Parent,
                    m =>
                    {
                        m.Columns(
                            cm =>
                            {
                                cm.Name("FirstName");
                                cm.Unique(false);
                            },
                            cm =>
                            {
                                cm.Name("SecondName");
                                cm.Unique(false);
                            });

                        m.Fetch(FetchKind.Join);
                        m.Class(typeof(Parent));
                    });

Same mapping throws an FK exception in .Net 8, and what is even more weird that some of the exceptions could be fixed with just reordering columns, but only in mapping, not in database FK. Note that FK columns order in database is different than columns order in mapping.

ALTER TABLE "SOME_TABLE" ADD CONSTRAINT "FC1_SOME_TABLE" FOREIGN KEY("FirstName", "SecondName") REFERENCES "SOME_PARENT_TABLE" ("FirstName", "SecondName")

idMapper.ManyToOne(
                    e => e.Parent,
                    m =>
                    {
                        m.Columns(
							cm =>	
                            {
                                cm.Name("SecondName");
                                cm.Unique(false);
                            },
                            cm =>
                            {
                                cm.Name("FirstName");
                                cm.Unique(false);
                            });

                        m.Fetch(FetchKind.Join);
                        m.Class(typeof(Parent));
                    });

[zdenotirc]

Issue was in incorrect mapping.