Java/RestTemplate - Allow flexible options in generated client when a file is needed

Created by: MosheElisha

Hi,

I have an API that requires a org.springframework.web.multipart.MultipartFile parameter (Swagger 2.0 API spec is below).

I am using generatorName=java and library=resttemplate to generate the client.

The generated Api client looks like:

public ResponseEntity<Template> createTemplateWithHttpInfo(File file, com.example.model.CreateTemplateRequest request) throws RestClientException {
...
    if (file != null)
            formParams.add("file", new FileSystemResource(file));
...

I would like to have the option to generate a client that takes an org.springframework.core.io.AbstractResource instead of a File. The user will be able to pass a new FileSystemResource(file) to have same behavior as now but if the user does not have the file on disk, he/she can use an InputStreamResource or a ByteArrayResource or ... For example:

    api.createTemplateWithHttpInfo(
        new ByteArrayResource(byteArray) {
          @Override
          public String getFilename() {
            return "memoryBytes";
          }
        },
        ...
    );

From the source code it seems that there is no such option: https://github.com/OpenAPITools/openapi-generator/blob/5cdc9e9e35b737b04a5a201446fb430a554ef5db/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/api.mustache#L133

I'm proposing a new configOption (something like "useAbstractionForFiles") and every library can try to support as possible (My first priority is to have the resttemplate library support this).

Swagger 2.0 API spec:

      "post" : {
        "operationId" : "createTemplate",
        "consumes" : [ "multipart/form-data" ],
        "produces" : [ "application/json" ],
        "parameters" : [ {
          "name" : "file",
          "in" : "formData",
          "required" : true,
          "type" : "ref"
        }, {
          "name" : "request",
          "in" : "formData",
          "required" : true,
          "type" : "ref"
        } ],
        "responses" : {
          "200" : {
            "description" : "successful operation",
            "schema" : {
              "$ref" : "#/definitions/Template"
            }
          },
          "201" : {
            "description" : ""
          }
        }
      }
    }