how to handle the before event in createOptionForm modal form

I have a problem, I can't figure out how to handle the before event in createOptionForm modal form

    ->before(function () {
        // Runs before the form fields are saved to the database.
    })

Full code

                Forms\Components\Select::make('agreement_id')
                    ->searchable()
                    ->preload()
                    ->relationship('agreement')
                    ->editOptionForm(AgreementResource::getForm())
                    ->createOptionForm(AgreementResource::getForm())
                    ->getOptionLabelFromRecordUsing(fn (Model $record) => "{$record->getShortNameAttribute()}"),