Magento 2.2.2 Plugin how to add custom field in request api

I’ve create a plugin to listen to api POST /V1/order/:orderId/refund and I would like to receive custom field. I’ve added a field for testing like: name:[‘test’] Body E.G: { “items”: [ { “extension_attributes”: {}, “order_item_id”: 7, “qty”: 1 } ], “isOnline”: false, “notify”: true, “appendComment”: true, “name”: [ { “test”: “ok” } ], //THIS IS…

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