Body not parsed correctly with Content-Type=application/json;charset=utf-8

[inneon]

Great repo - thanks for all the hard work.

The body is not parsed correctly when I send the Content-Type of application/json;charset=utf-8.

Minimal example

post-device.json:

{
  "description": "Creates a new device",
  "request": {
    "method": "POST",
    "path": "/devices",
    "headers": {
      "Content-Type":["application/json;charset=utf-8"] // Note- this line can be omitted with the same result
    }
  },
  "response": {
    "statusCode": 201,
    "headers": {
      "Content-Type": ["application/json"]
    },
    "body": "{\"deviceId\": \"{{fake.UUID}}\", \"externalId\":\"{{request.body.externalId}}\" }"
  },
  "control": {
    "priority": 10
  }
}

Failing request from the console

{
    "scheme": "http",
    "host": "localhost",
    "port": "8083",
    "method": "POST",
    "path": "/devices",
    "queryStringParameters": {},
    "fragment": "",
    "headers": {
        "Accept": [
            "*/*"
        ],
        "Accept-Encoding": [
            "gzip, deflate, br"
        ],
        "Connection": [
            "keep-alive"
        ],
        "Content-Length": [
            "29"
        ],
        "Content-Type": [
            "application/json;charset=utf-8"
        ],
        "Postman-Token": [
            "769d6d8c-3060-40f7-baf0-8d4a859bcf69"
        ],
        "User-Agent": [
            "PostmanRuntime/7.33.0"
        ]
    },
    "cookies": {},
    "body": "{\"externalId\":\"BC572903D0B6\"}"
}

Failing response (notice how {{request.body.externalId}} is present in the response body).

{
    "statusCode": 201,
    "headers": {
        "Content-Type": [
            "application/json"
        ]
    },
    "cookies": null,
    "body": "{\"deviceId\": \"2e904f11-a17b-4366-8772-3db85e4bc2bd\", \"externalId\":\"{{request.body.externalId}}\" }"
}

Working request - note that content type has changed to be "application/json" (no charset).

{
    "scheme": "http",
    "host": "localhost",
    "port": "8083",
    "method": "POST",
    "path": "/devices",
    "queryStringParameters": {},
    "fragment": "",
    "headers": {
        "Accept": [
            "*/*"
        ],
        "Accept-Encoding": [
            "gzip, deflate, br"
        ],
        "Connection": [
            "keep-alive"
        ],
        "Content-Length": [
            "29"
        ],
        "Content-Type": [
            "application/json"
        ],
        "Postman-Token": [
            "af6fcf80-e439-427d-a3cd-005bff4e50d6"
        ],
        "User-Agent": [
            "PostmanRuntime/7.33.0"
        ]
    },
    "cookies": {},
    "body": "{\"externalId\":\"BC572903D0B6\"}"
}

Working response

{
    "statusCode": 201,
    "headers": {
        "Content-Type": [
            "application/json"
        ]
    },
    "cookies": null,
    "body": "{\"deviceId\": \"b3479472-bd23-42c1-ad15-312eb9634434\", \"externalId\":\"BC572903D0B6\" }"
}