Laravel join table with null

i want join 2 table with spesifik data, like supplyments where id is 1 but get all data from the other table, i test with this code and success but when id is not 1 but not null in supplyments data from other table not show, from that output as you can see id 3 in supply_categories not show because id is not 1 but not null too

$this->hasMany(Supplyment::class, 'id_user')
     ->rightJoin('supply_categories as category', 'category.id', '=', 'supplyments.id_category')
     ->orWhereNull('supplyments.id_user');

output

"supplyment": [
        {
            "id": 1,
            "name": "egg",
            "id_user": 1
        },
        {
            "id": 2,
            "name": "glass",
            "id_user": 1
        },
        {
            "id": 4,
            "name": "table",
            "id_user": null
        }
    ]