How to update quantityAvailable of a product in an inventory via API?

In Payload of Step 1 what is inventoryItem.id and where can I get it?

I have created two Bin Locations - Store and Sold - under my location and after moving the product from Default location to Store location I tried to get inventoryItem.id from
GET /openboxes/api/products/2c96808386c648e70186c69efed0000b/availableItems
Response

{
    "data": [
        {
            "inventoryItem.id": "2c96808386c648e70186c6adf57c000c",
            "product.name": "test product 1",
            "product": {
                "id": "2c96808386c648e70186c69efed0000b",
                "productCode": "tp1",
                "name": "test product 1",
                "description": null,
                "category": "test category",
                "unitOfMeasure": null,
                "pricePerUnit": 1,
                "dateCreated": "2023-03-09T13:45:54Z",
                "lastUpdated": "Mar 10, 2023",
                "updatedBy": "Miss Administrator",
                "color": null,
                "handlingIcons": [],
                "lotAndExpiryControl": false,
                "active": true
            },
            "productCode": "tp1",
            "lotNumber": null,
            "expirationDate": null,
            "binLocation": {
                "id": "2c96808386da37c80186dc7cb9f90017",
                "name": "Store",
                "description": null,
                "locationNumber": null,
                "locationGroup": null,
                "parentLocation": {
                    "id": "2c96808386da37c80186dc7c32520015",
                    "name": "test merchant",
                    "description": null,
                    "locationNumber": null,
                    "locationGroup": null,
                    "parentLocation": null,
                    "locationType": {
                        "id": "2c96808386c648e70186c87661f1002d",
                        "name": "super",
                        "description": null,
                        "locationTypeCode": "DISTRIBUTOR"
                    },
                    "sortOrder": null,
                    "hasBinLocationSupport": true,
                    "hasPackingSupport": true,
                    "hasPartialReceivingSupport": true,
                    "hasCentralPurchasingEnabled": true,
                    "organizationName": "tst",
                    "organizationCode": "TST",
                    "backgroundColor": "FFFFFF",
                    "zoneName": null,
                    "zoneId": null,
                    "active": true,
                    "organization": {
                        "id": "2c96808386c648e70186c67a9c6b0004",
                        "name": "tst",
                        "description": null,
                        "code": "TST",
                        "dateCreated": "2023-03-09T13:06:10Z",
                        "lastUpdated": "2023-03-09T13:06:10Z",
                        "defaultLocation": null,
                        "partyType": {
                            "id": "1",
                            "name": "Organization",
                            "code": "ORG",
                            "partyTypeCode": "ORGANIZATION"
                        },
                        "roles": [
                            {
                                "id": "2c96808386c648e70186c67c40fa0006",
                                "roleType": "ROLE_ORGANIZATION",
                                "startDate": null,
                                "endDate": null
                            }
                        ],
                        "sequences": {}
                    },
                    "manager": {
                        "id": "1",
                        "name": "Miss Administrator",
                        "firstName": "Miss",
                        "lastName": "Administrator",
                        "email": "admin@openboxes.com",
                        "username": "admin"
                    },
                    "address": null,
                    "supportedActivities": [
                        "PARTIAL_RECEIVING",
                        "DYNAMIC_CREATION",
                        "EXTERNAL",
                        "PLACE_ORDER",
                        "ENABLE_NOTIFICATIONS",
                        "ADJUST_INVENTORY",
                        "HOLD_STOCK",
                        "SUBMIT_REQUEST",
                        "REQUIRE_ACCOUNTING",
                        "MANAGE_INVENTORY",
                        "APPROVE_ORDER",
                        "PICK_STOCK",
                        "FULFILL_REQUEST",
                        "PLACE_REQUEST",
                        "PUTAWAY_STOCK",
                        "SEND_STOCK",
                        "CROSS_DOCKING",
                        "ENABLE_CENTRAL_PURCHASING",
                        "CONSUME_STOCK",
                        "PACK_SHIPMENT",
                        "FULFILL_ORDER",
                        "RECEIVE_STOCK",
                        "APPROVE_REQUEST"
                    ]
                },
                "locationType": {
                    "id": "cab2b4f35ba2d867015ba2e17e390001",
                    "name": "Bin Location",
                    "description": "Default bin location type",
                    "locationTypeCode": "BIN_LOCATION"
                },
                "sortOrder": null,
                "hasBinLocationSupport": true,
                "hasPackingSupport": false,
                "hasPartialReceivingSupport": false,
                "hasCentralPurchasingEnabled": false,
                "organizationName": "tst",
                "organizationCode": "TST",
                "backgroundColor": "FFFFFF",
                "zoneName": null,
                "zoneId": null,
                "active": true,
                "organization": {
                    "id": "2c96808386c648e70186c67a9c6b0004",
                    "name": "tst",
                    "description": null,
                    "code": "TST",
                    "dateCreated": "2023-03-09T13:06:10Z",
                    "lastUpdated": "2023-03-09T13:06:10Z",
                    "defaultLocation": null,
                    "partyType": {
                        "id": "1",
                        "name": "Organization",
                        "code": "ORG",
                        "partyTypeCode": "ORGANIZATION"
                    },
                    "roles": [
                        {
                            "id": "2c96808386c648e70186c67c40fa0006",
                            "roleType": "ROLE_ORGANIZATION",
                            "startDate": null,
                            "endDate": null
                        }
                    ],
                    "sequences": {}
                },
                "manager": null,
                "address": null,
                "supportedActivities": [
                    "PICK_STOCK",
                    "PUTAWAY_STOCK"
                ]
            },
            "zone": null,
            "quantityAvailable": 10,
            "quantityOnHand": null,
            "status": "AVAILABLE",
            "pickedRequisitionNumbers": "",
            "binLocation.id": "2c96808386da37c80186dc7cb9f90017",
            "binLocation.name": "Store"
        }
    ]
}

and use it in payload for
POST /openboxes/api/stockTransfers
Payload

{
    "stockTransferItems": [
        {
            "product.id": "2c96808386c648e70186c69efed0000b",
            "product.productCode": "tp1",
            "inventoryItem.id": "2c96808386c648e70186c6adf57c000c",
            "location.id": "2c96808386da37c80186dc7c32520015",
            "lotNumber": "Default",
            "originBinLocation.id": "2c96808386da37c80186dc7cb9f90017",
            "destinationBinLocation.id": "2c96808386da37c80186dc7ccfd70019",
            "quantity": 1
        }
    ]
}

It seems that it correctly creates stock transfer in PENDING status and I can see it in UI
Response

{
    "data": {
        "id": "2c96808386da37c80186dc84235a0022",
        "description": null,
        "stockTransferNumber": "827MHK",
        "status": "PENDING",
        "dateCreated": "March 13, 2023",
        "origin.id": "2c96808386da37c80186dc7c32520015",
        "origin.name": "test merchant",
        "destination.id": "2c96808386da37c80186dc7c32520015",
        "destination.name": "test merchant",
        "stockTransferItems": [
            {
                "id": "2c96808386da37c80186dc84235a0023",
                "productAvailabilityId": "2c96808386da37c80186dc84235a0023",
                "product.id": "2c96808386c648e70186c69efed0000b",
                "product.productCode": "tp1",
                "product.name": "test product 1",
                "product.handlingIcons": [],
                "inventoryItem.id": "2c96808386da37c80186dc73fb6c000e",
                "lotNumber": "Default",
                "expirationDate": null,
                "recalled": false,
                "originBinLocation.id": "2c96808386da37c80186dc7cb9f90017",
                "originBinLocation.name": "Store",
                "originZone": null,
                "onHold": false,
                "destinationBinLocation.id": "2c96808386da37c80186dc7ccfd70019",
                "destinationBinLocation.name": "Sold",
                "destinationZone.id": null,
                "destinationZone.name": null,
                "quantity": 1,
                "quantityOnHand": 0,
                "quantityNotPicked": 0,
                "status": "PENDING",
                "recipient": null,
                "splitItems": [],
                "picklistItems": [],
                "sortOrder": 0
            }
        ],
        "orderedBy": "Miss Administrator",
        "type": "TRANSFER_ORDER",
        "dateShipped": "",
        "expectedDeliveryDate": "",
        "shipmentType": "",
        "trackingNumber": "",
        "driverName": "",
        "comments": "",
        "documents": ""
    }
}

but when I try to update this transfer with ID I get from the previous step
POST /openboxes/api/stockTransfers/2c96808386da37c80186dc84235a0022
Payload

{
    "status": "COMPLETED"
}

I always get a response with an empty stockTransferItems array
Response

{
    "data": {
        "id": "2c96808386da37c80186dc8454940024",
        "description": null,
        "stockTransferNumber": "355YBV",
        "status": "COMPLETED",
        "dateCreated": "March 13, 2023",
        "origin.id": "2c96808386da37c80186dc7c32520015",
        "origin.name": "test merchant",
        "destination.id": "2c96808386da37c80186dc7c32520015",
        "destination.name": "test merchant",
        "stockTransferItems": [],
        "orderedBy": "Miss Administrator",
        "type": "TRANSFER_ORDER",
        "dateShipped": "",
        "expectedDeliveryDate": "",
        "shipmentType": "",
        "trackingNumber": "",
        "driverName": "",
        "comments": "",
        "documents": ""
    }
}

And in UI I see a new completed transfer with 0 items in it.