[BUG] [java-jaxrs-resteasy] JacksonConfig.java uses wrong date library

[NaigoApps]

I'm using openapi-generator-maven-plugin to generate some classes given a yaml file. I wanted to use java8 as date library, but it seems that I'll need to add a dependency to joda library as well, because generated code refers that library despite configuration.

Tool used: openapi-generator-maven-plugin version 4.2.3

Plugin configuration:

<configuration>
	<inputSpec>${project.basedir}/src/main/resources/api/swagger/api.yaml</inputSpec>
	<generatorName>jaxrs-resteasy</generatorName>
	<configOptions>
		<sourceFolder>src/main/java/api/generated</sourceFolder>
		<dateLibrary>java8</dateLibrary>
	</configOptions>
</configuration>

api.yaml

openapi: 3.0.0
info:
  title: My API
  description: My API
  version: 1.0.0
servers:
  - url: myapi.com

paths:
  /users:
    get:
      summary: 'Gets all users'
      tags: ['users']
      responses:
        '200':
          description: 'List of users'
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/User'
components:
  schemas:
    User:
      type: object
      properties:
        username:
          type: string
        registerDate:
          type: string
          format: date
        roles:
          type: array
          items:
            $ref: '#/components/schemas/UserRole'
    UserRole:
      type: string
      enum:
        - CLIENT
        - EXPERT
        - ADMIN

User class is generated correctly, as I found field registerDate of type LocalDate
User.java

public class User   {
	private String username;
	private LocalDate registerDate;
	private List<UserRole> roles = new ArrayList<>();
//other generated code...
}

The generator generates the JacksonConfig class as well, but this uses joda date library, even if I specified java8 in plugin configuration. I saw JacksonConfig.mustache, and I can't find customizable content.
JacksonConfig.mustache

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;
import com.fasterxml.jackson.datatype.joda.JodaModule
import org.joda.time.DateTime;
import org.joda.time.LocalDate;
import org.joda.time.format.ISODateTimeFormat;

import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;
import java.io.IOException;

@Provider
public class JacksonConfig implements ContextResolver<ObjectMapper> {
    private final ObjectMapper objectMapper;

    public JacksonConfig() throws Exception {

        objectMapper = new ObjectMapper()
            .setDateFormat(new RFC3339DateFormat())
            .registerModule(new JodaModule() {
                {
                    addSerializer(DateTime.class, new StdSerializer<DateTime>(DateTime.class) {
                        @Override
                        public void serialize(DateTime value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonGenerationException {
                            jgen.writeString(ISODateTimeFormat.dateTimeNoMillis().print(value));
                        }
                    });
                    addSerializer(LocalDate.class, new StdSerializer<LocalDate>(LocalDate.class) {
                        @Override
                        public void serialize(LocalDate value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonGenerationException {
                            jgen.writeString(ISODateTimeFormat.date().print(value));
                        }
                    });

                }
            });
    }

    public ObjectMapper getContext(Class<?> arg0) {
        return objectMapper;
    }
}

[albertotn]

As part of hacktoberfest 2020 I'd like to try and solve this

[alwibrm]

@albertotn Would appreciate a bugfix here. I just ran into the problem, too.

[wing328]

We welcome contributions from the community to fix it or someone to sponsor this fix to give it a higher priority among other requests.

[lostiniceland]

Would it be possible to backport this fix to 4.3.x
Due to the inheritance-bug we have to downgrade the plugin from 5.x to 4.3.1 which now generates the wrong date imports