[JAVA SPRING] String parameter with format uuid not generated as java.util.UUID

Description

Similar issue as explained in the related issue. String properties and containered type (like List<?>) with format uuid are generated properly, but parameters of type string and format uuid are not.

Swagger-codegen version

3.0.3

Swagger declaration file content or url

swagger: "2.0"
info:
  description: "This is a sample server..."
  version: "1.0.0"
  title: "Swagger Petstore"
  termsOfService: "http://swagger.io/terms/"
  contact:
    email: "apiteam@swagger.io"
  license:
    name: "Apache 2.0"
    url: "http://www.apache.org/licenses/LICENSE-2.0.html"
host: "petstore.swagger.io"
basePath: "/v2"
schemes:
- "https"
- "http"
paths:
  '/operators/{operatorId}/watchlist/add':
    post:
      tags:
        - Products
      parameters:
        - name: operatorId
          in: path
          description: ID of operator
          required: true
          type: string
          format: uuid
        - name: productIds
          in: body
          description: array of product Ids
          required: true
          schema:
            type: array
            items:
              type: string
              format: uuid
      responses:
        '200':
          description: Added successfuly

Generated code

default ResponseEntity<Void> _operatorsOperatorIdWatchlistAddPost(@ApiParam(value = "array of product Ids" ,required=true )  @Valid @RequestBody List<UUID> body,@ApiParam(value = "ID of operator",required=true) @PathVariable("operatorId") String operatorId) {
        return operatorsOperatorIdWatchlistAddPost(body,operatorId);
    }

Related issues/PRs

https://github.com/swagger-api/swagger-codegen/issues/1806#issuecomment-449035297

Workaround

I am currently using a custom generator to fix that issue.
It's quite naive solution since it adds the import to all api interfaces no matter if it's required in any of the methods.

package generators

import io.swagger.codegen.v3.CodegenParameter
import io.swagger.codegen.v3.generators.java.SpringCodegen
import java.util.regex.Pattern

class ExtendedSpringCodegen extends SpringCodegen {

    void postProcessParameter(CodegenParameter parameter) {
        if (Objects.isNull(parameter.dataType) || Objects.isNull(parameter.dataFormat)) {
            return
        }
        if (parameter.dataType.equalsIgnoreCase("string")) {
            if (parameter.dataFormat.equalsIgnoreCase("uuid")) {
                parameter.dataType = "UUID"
            }
        }
    }

    Map<String, Object> postProcessOperations(Map<String, Object> objs) {
        objs = super.postProcessOperations(objs)
        List<Map<String, String>> imports = (List<Map<String, String>>) objs.get("imports")
        Pattern pattern = Pattern.compile("java\\.util\\.UUID")
        for (Iterator<Map<String, String>> itr = imports.iterator(); itr.hasNext();) {
            String _import = itr.next().get("import")
            if (pattern.matcher(_import).matches()) {
                return objs
            }
        }
        imports.add(new HashMap<String, String>() {{ put("import", "java.util.UUID") }})
        return objs
    }

}

Start with the SpringCodegen entry points shown in the workaround, especially postProcessParameter and postProcessOperations, and reproduce the issue using the provided Swagger 2.0 YAML. Compare the generated path parameter with the UUID body element; done means a string parameter with format uuid is generated as java.util.UUID with the required import.