[BUG] [typescript] Get Parameter Object not serialized properly

Description

I am trying to serialize an object into an array.
The GET Url should be generated like this
http://localhost/index?filter[contact]=101d71e1-745e-4efc-8341-ad204bb1c5c7&page=1&count=8

but it generates like this
http://localhost/index/?filter=%5Bobject%20Object%5D&page=1&count=8

openapi-generator version

5.0.0-beta

OpenAPI declaration file content or url

{
   "openapi":"3.0.0",
   "info":{
      "title":"Demo API",
      "description":"",
      "version":"1.0.0"
   },
   "servers":[
      {
         "url":"http:\/\/localhost"
      }
   ],
   "paths":{
      "\/index":{
         "get":{
            "tags":[
               "Index"
            ],
            "summary":"Returns all Index.",
            "operationId":"search",
            "parameters":[
               {
                  "name":"filter",
                  "in":"query",
                  "schema":{
                     "$ref":"#\/components\/schemas\/IndexFilterType"
                  }
               },
               {
                  "name":"page",
                  "in":"query",
                  "description":"The page number",
                  "schema":{
                     "type":"number"
                  }
               },
               {
                  "name":"count",
                  "in":"query",
                  "description":"items per page to load",
                  "schema":{
                     "type":"number"
                  }
               }
            ],
            "responses":{
               "200":{
                  "description":"",
                  "content":{
                     "application\/json":{
                        "schema":{
                           "$ref":"#\/components\/schemas\/IndexResponse"
                        }
                     }
                  }
               }
            }
         },
      }
   },
   "components":{
      "schemas":{
         "IndexFilterType":{
            "type":"object",
            "properties": {
                "contact": {
                    "type": "string"
                }
            },
         },
         "IndexResponse":{
            "properties":{
               "status":{
                  "type":"string"
               },
               "data":{
                  "type":"array",
                  "items":{
                     "$ref":"#\/components\/schemas\/MetaDto"
                  }
               },
               "total":{
                  "type":"number"
               },
               "pages":{
                  "type":"number"
               }
            },
            "type":"object"
         },
         "MetaDto":{
            "properties":{
               "id":{
                  "type":"string"
               },
               "contact":{
                  "$ref":"#\/components\/schemas\/ContactDto"
               },
               "lead":{
                  "$ref":"#\/components\/schemas\/ContactDto"
               },
               "title":{
                  "type":"string"
               },
               "number":{
                  "type":"integer"
               }
            },
            "type":"object"
         },
         "ContactDto":{
            "properties":{
               "id":{
                  "type":"string"
               },
               "display_name":{
                  "type":"string"
               },
               "short_name":{
                  "type":"string"
               },
               "initials":{
                  "type":"string"
               },
               "type":{
                  "type":"string"
               },
               "pre_name":{
                  "type":"string"
               },
               "last_name":{
                  "type":"string"
               },
               "title":{
                  "type":"string"
               },
               "sex":{
                  "type":"string"
               },
               "company_name":{
                  "type":"string"
               },
               "birthday":{
                  "type":"string"
               },
               "tax_id":{
                  "type":"string"
               },
               "salutation":{
                  "type":"string"
               },
               "avatar":{
                  "$ref":"#\/components\/schemas\/FileMetaDto"
               }
            },
            "type":"object"
         },
         "FileMetaDto":{
            "properties":{
               "id":{
                  "type":"string"
               },
               "filename":{
                  "type":"string"
               },
               "mime_type":{
                  "type":"string"
               },
               "file_size":{
                  "title":"Filesize in Bytes",
                  "type":"integer"
               },
               "url":{
                  "type":"string"
               }
            },
            "type":"object"
         }
      }
   }
}

Generation Details

openapi-generator generate -i http://localhost/swagger.json -g typescript

Steps to reproduce

1. See schema and generation details

Related issues/PRs

Maybe this? https://github.com/OpenAPITools/openapi-generator/issues/100

Start by reproducing the generated TypeScript client from the supplied OpenAPI declaration with the shown openapi-generator command, then trace its GET query-parameter serialization. Done means the filter object produces a URL containing filter[contact]=101d71e1-745e-4efc-8341-ad204bb1c5c7 instead of [object Object], while page and count remain serialized.