Removing an element from a list doesn't actually remove it

[torbjorn-boost]

Hello. I hope this is the right place for this issue, and that it has enough information:

So I have these two classes:

class Lol {

    Long id
    String name

    List<Omg> omgs = new ArrayList<>()

    static hasMany = [
        omgs: Omg
    ]

    static mappedBy = [
        omgs: 'lol'
    ]

    static mapping = {
        id generator: 'sequence', params:[sequence:'lol_seq']
        omgs indexColumn: [
            name: 'lol_index'
        ]
    }
}

package ai.boost

class Omg {

    Long id
    String name

    Lol lol

    static constraints = {
        lol nullable: true
    }

    static mapping = {
        id generator: 'sequence', params: [sequence: 'omg_seq']
    }
}

And the SQL:

CREATE SEQUENCE lol_seq;
CREATE TABLE lol (
  id BIGINT PRIMARY KEY DEFAULT NEXTVAL('lol_seq'),
  name text
);

CREATE SEQUENCE omg_seq;
CREATE TABLE omg (
  id BIGINT PRIMARY KEY DEFAULT NEXTVAL('omg_seq'),
  name text,
  lol_id BIGINT REFERENCES lol(id),
  lol_index INT
);

Basically, a Lol has an ordered list of omgs.

The following code works fine:

Lol lol = new Lol(name: 'Lol 1');
Omg omg1 = new Omg(name: 'Omg 1')
Omg omg2 = new Omg(name: 'Omg 2')
Omg omg3 = new Omg(name: 'Omg 3')
lol.addToOmgs(omg1)
lol.addToOmgs(omg2)
lol.addToOmgs(omg3)
lol.save(flush: true)

I mean, look at this, it's just what I want: Beatiful!

But, what happens if I want to remove one of the omgs from the list without deleting it?

Lol lol = new Lol(name: 'Lol 1');
Omg omg1 = new Omg(name: 'Omg 1')
Omg omg2 = new Omg(name: 'Omg 2')
Omg omg3 = new Omg(name: 'Omg 3')
lol.addToOmgs(omg1)
lol.addToOmgs(omg2)
lol.addToOmgs(omg3)

lol.save(flush: true)

lol.removeFromOmgs(omg2) // Just added this line

This: What is this? lol_id is still 1, but, in my opinion, should be NULL, and the same with lol_index.

Things I tried that had no effect:

• omg2.setLol(null)
• Adding nullable: true to the indexColumn
• Upgrading from gorm 6.1.9 to 6.1.12