Camel Swagger API response message headers of type string generate an empty enum even when allowableValues are not specified.

rest().get("/test") 
.responseMessage().code(200).header("header1").description("test_header")
.endHeader().endResponseMessage() .to("log:log1?showBody=true");

{
  "swagger" : "2.0",
  "info" : {
    "version" : "1.0",
    "title" : "Test API"
  },
  "host" : "localhost:8080",
  "basePath" : "/rest",
  "schemes" : [ "http" ],
  "paths" : {
    "/test" : {
      "get" : {
        "operationId" : "verb1",
        "responses" : {
          "200" : {
            "description" : "success",
            "headers" : {
              "header1" : {
                "type" : "string",
                "description" : "test_header",
                "enum" : [ ]
              }
            }
          }
        }
      }
    }
  }
}