title: Why does Swagger UI POST form data with Content-Type: undefined?
body: <p>I'm trying to POST form data using Swagger UI, but the request is sent with <code>Content-Type: undefined</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/wsR3C.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wsR3C.png" alt="enter image description here"></a></p>
  
  <p>How can I configure it so it works? JSON POST works just fine.</p>
  
  <p>Here is my API definition:</p>
  
  <pre class="lang-js prettyprint-override"><code>{
    "swagger": "2.0",
    "info": {
      "version": "V1",
      "title": "Title"
    },
    "paths": {
      "/api/getcalculation": {
        "post": {
          "tags": [
            "ArrearsOfPay"
          ],
          "operationId": "ApiArrearsOfPayPost",
          "consumes": [],
          "produces": [
            "application/json"
          ],
          "parameters": [
            {
              "name": "InsolvencyDate",
              "in": "formData",
              "required": false,
              "type": "string",
              "format": "date-time"
            },
            {
              "name": "DismissalDate",
              "in": "formData",
              "required": false,
              "type": "string",
              "format": "date-time"
            },
            {
              "name": "UnpaidPeriodFrom",
              "in": "formData",
              "required": false,
              "type": "string",
              "format": "date-time"
            },
            {
              "name": "UnpaidPeriodTo",
              "in": "formData",
              "required": false,
              "type": "string",
              "format": "date-time"
            },
            {
              "name": "ApClaimAmount",
              "in": "formData",
              "required": false,
              "type": "number",
              "format": "double"
            },
            {
              "name": "PayDay",
              "in": "formData",
              "required": false,
              "type": "integer",
              "format": "int32"
            },
            {
              "name": "ShifPattern",
              "in": "formData",
              "required": true,
              "type": "array",
              "items": {
                "type": "string"
              },
              "collectionFormat": "multi"
            },
            {
              "name": "WeeklyWage",
              "in": "formData",
              "required": false,
              "type": "number",
              "format": "double"
            },
            {
              "name": "StatutaryMax",
              "in": "formData",
              "required": false,
              "type": "number",
              "format": "double"
            },
            {
              "name": "NumberOfDaysWorkedInWeek",
              "in": "formData",
              "required": false,
              "type": "integer",
              "format": "int32"
            }
          ],
          "responses": {
            "200": {
              "description": "Success",
              "schema": {
                "$ref": "#/definitions/ArrearsOfPayCalculationResponseModel"
              }
            }
          }
        }
      }
    },
    "definitions": {
      "ArrearsOfPayCalculationResponseModel": {
        "type": "object",
        "properties": {
          "startOfPayWeek": {
            "format": "date-time",
            "type": "string"
          },
          "maximumLiability": {
            "format": "double",
            "type": "number"
          },
          "employerLiability": {
            "format": "double",
            "type": "number"
          },
          "minimumLiability": {
            "format": "double",
            "type": "number"
          }
        }
      }
    }
  }
  </code></pre>