Simple JSON String cause can't parse JSON. Raw result:

Having a simple REST GET request runnig in Swagger-UI cause this issue.
The server returns the simple JSON String "Hello World".
The issue is reproducable in Firefox, Edge and Chrome.

• Swagger UI version: 3.20.9
• swagger-core version: 2.0.7

openApiDefinition:

{
  "openapi" : "3.0.1",
  "info" : {
    "title" : "Simple Rest",
    "description" : "",
    "version" : "1.0"
  },
  "servers" : [ {
    "url" : ""
  } ],
  "paths" : {
      "/helloWorld" : {
      "get" : {
        "tags" : [ "Miscellaneous" ],
        "summary" : "Test helloWorld",
        "description" : "helloWorld ",
        "operationId" : "helloWorld",
        "responses" : {
          "200" : {
            "description" : "helloWorld on success",
            "content" : {
              "application/json" : {
                "schema" : {
                  "type" : "string"
                }
              }
            }
          }
        }
      }
    }
  }
}

Reproduce the /helloWorld GET request in Swagger UI 3.20.9 using the supplied OpenAPI definition and a response containing the JSON string "Hello World". Trace the response parsing from the Swagger UI request entry point, then verify that the response renders without a JSON parse error in Firefox, Edge, and Chrome.