can't understand how to write function from description

[toxic kiln]

Hello! I'm struggling to put this thing into a function to check all 3. I'm trying to replicate this in a unit test but can't seem to progress anywhere.
For each repairTeamUserIds value, a check is made for records found where Repair_team_user.USER_ID = repairTeamUserIds[n]

1. If present, it is not changed
2. If not, a new record is added
3. If there is a record in the database with a Repair_team_user.USER_ID value that is not found in the repairTeamUserIds list, the record is deleted from the database

        final var repairTeams = new ArrayList<>(List.of(1, 2, 3));
        final var repairTeamUserIds = new ArrayList<>(List.of(1, 2, 4));

        request.getRepairTeamUserIds().forEach(userId -> {
            for (RepairTeam repairTeam : repairTeams) {
                if (!Objects.equals(userId, repairTeam.getUser().getId())) {
                    repairTeamRepository.delete(repairTeam);
                } else {
                    final var newRepairTeam = new RepairTeam();
                    newRepairTeam.setRepair(repair);
                    newRepairTeam.setUser(user);

                    repairTeamRepository.save(newRepairTeam);
                }
            }
        });

[mild minnow]

<@&987246399047479336> please have a look, thanks.

[mild minnow]

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