Schema definition in Swagger

Question

I'm very new to OpenAPI and I'm using http://editor.swagger.io to design an API. I'm stuck in Schema with a JSON looking like following

{
  "CORRELATION_ID": "10",
  "CONTROL":
  {
    "DAS_IS_RECIPIENT": "123",
    "DOCTPYE": "ert",
    "PROCESS_INDICATOR": "nord"
  },
  "HEADER":
  {
    "ID": "456",
    "INVOICE_NUMBER": "678",
    "DMS_DOC_ID": "876",
    "INVOICE_DATE": "10082020"
  },
  "ITEMS": [
    {
      "SHORT_TEXT": "123",
      "LSTAR": 0,
      "QUANTITY": "23"
    },
    {
      "SHORT_TEXT": "456",
      "LSTAR": 234,
      "QUANTITY": "21"
    }
  ],
  "DEBITOR":
  {
    "ID": "444",
    "FIRSTNAME": "nick",
    "LASTNAME": "cantre"
  },
  "CREDITOR":
  {
    "ID": "454",
    "FIRSTNAME": "ava",
    "LASTNAME": "pierre"
  }
}

How to create a schema according to this JSON structure?