CustomFields of type Json is saved only after json_encode() in address update

Shopware 6 (English)
1

Hi eveyone I am facing an issue with something I want to achieve. The system version is 6.4.18.1

My goal

I need to save customFields of type Json on address upsert this to store some data that will be retrieved afterwards.

What i have already done

plugin configuration

created custom fields (with „allowCustomerWrite“ = true) and custom fields set

        $customerAddressPrefix = [
            'name' => 'customer_prefix',
            'config' => [
                'label' => [
                    'de-DE' => ' '
                ],
            ],
            "relations" => [
                [
                    "entityName" => CustomerAddressDefinition::ENTITY_NAME,
                ],
            ],
            'customFields' => [
                [
                    'name' => 'customer_address_prefix',
                    'type' => CustomFieldTypes::JSON,
                    "allowCustomerWrite" => true, 
                    'config' => [
                        'label' => [
                            'de-DE' => '',
                        ],
                        'helpText' => [
                            'de-DE' => '',
                        ],
                        'customFieldPosition' => 1,
                    ],
                ],
            ],
        ];

UpsertAddressRouteDecorator

Added customFields to DataBag as follows

        $address= $data->get("address");
        $address->set(
            "customFields",
            new RequestDataBag([
                "customer_address_prefix" =>
//              THIS DID NOT WORK -> result in {"customer_address_prefix" => {}}
//                    [[
//                        'type' => "aaaa",
//                        'prefix' => "bbbb",
//                        'id' => $genericAddress->get("id"),
//                    ]],
//                NEITHER THIS WORKED -> result in  {"customer_address_prefix" => {}}
//                     RequestDataBag([
//                        'type' => "aaaa",
//                        'prefix' => "bbbb",
//                        'id' => $genericAddress->get("id"),
//                    ]),
                    json_encode([
                        'type' => $billingOrShipping,
                        'prefix' => $cleanPhonePrefix,
                        'id' => $genericAddress->get("id"),
                    ], JSON_THROW_ON_ERROR),
            ])
        );

Actual problem

I cannot store customFields in Json format other that passing it with json_encode(). But having so can lead to problem afterwards. Therefore I wanted to know whether anyone knows a way to store it (via DataBag) in Json format.

Thanks for you time and patience