jaxrs-jersey: Problem with nonexisting import and wildcard responsecode

Description

The generator creates non compilable java code.

Contains the response a schema with oneOf, the created code references to an class OneOfxxx. In my examlple de.test.openapi.server.model.OneOfCatDog. But the file will not be generated, so the code doesn't compile.

Furthermore if I add a wildcard response like '5XX' as described here https://swagger.io/docs/specification/describing-responses/. I'll get an annotation like this @io.swagger.annotations.ApiResponse(code = 5XX, message = "General server error", response = Void.class The problem here is, that code is defined as an integer. So it won't compile.

openapi-generator version

openapi-generator-maven-plugin 4.2.3

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: Swagger Petstore
  description: 'This is a sample server Petstore server.  You can find out more about     Swagger
    at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).      For
    this sample, you can use the api key `special-key` to test the authorization     filters.'
  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
  version: 1.0.0
externalDocs:
  description: Find out more about Swagger
  url: http://swagger.io
servers:
- url: https://petstore.swagger.io/v2
- url: http://petstore.swagger.io/v2
paths:
  /petData/{type}/{id}:
    get:
      summary: Description
      description: Get
      operationId: getPet
      parameters:
        - in: path
          name: type
          description: reference for dataType
          required: true
          schema:
            $ref: '#/components/schemas/Datatypes'
        - in: path
          name: id
          description: reference 
          required: true
          schema:
            type: string
      responses:
        '200':
          description: deliver existing data
          content:
            application/json:
              schema:
                oneOf:
                  - $ref: '#/components/schemas/Cat'
                  - $ref: '#/components/schemas/Dog'
        '5XX':
          description: General server error
          content: {}
      security:
      - petstore_auth:
        - write:pets
        - read:pets
      x-codegen-request-body-name: body
    
components:
  schemas:
    Datatypes:
      type: string
      enum: [cat, dog]
    
    Cat:
      type: object
      required: [id]
      properties:
        id:
          type: string
        name:
          type: string
        age:
          type: integer
    Dog:
      type: object
      required: [id]
      properties:
        id:
          type: string
        name:
          type: string
  securitySchemes:
    petstore_auth:
      type: oauth2
      flows:
        implicit:
          authorizationUrl: http://petstore.swagger.io/oauth/dialog
          scopes:
            write:pets: modify pets in your account
            read:pets: read your pets
    api_key:
      type: apiKey
      name: api_key
      in: header

Command line used for generation

<?xml version="1.0"?>
<project
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
	xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<modelVersion>4.0.0</modelVersion>
	<groupId>de.test</groupId>
	<artifactId>openapi</artifactId>
	<name>openapi test</name>
	<version>1.0.0-SNAPSHOT</version>


	<properties>
		<java.version>1.8</java.version>
		<maven.compiler.source>${java.version}</maven.compiler.source>
		<maven.compiler.target>${java.version}</maven.compiler.target>
		<swagger-core-version>1.5.18</swagger-core-version>
		<beanvalidation-version>1.1.0.Final</beanvalidation-version>
		<jersey2-version>2.22.2</jersey2-version>
		<jackson-version>2.9.9</jackson-version>
		<junit-version>4.13</junit-version>
		<logback-version>1.1.7</logback-version>
		<servletapi-version>3.1.0</servletapi-version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>io.swagger</groupId>
			<artifactId>swagger-jersey2-jaxrs</artifactId>
			<scope>compile</scope>
			<version>${swagger-core-version}</version>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<version>${logback-version}</version>
			<scope>compile</scope>
		</dependency>

		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-core</artifactId>
			<version>${logback-version}</version>
			<scope>compile</scope>
		</dependency>
		
		<!-- <dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>2.5</version>
		</dependency> -->
		
		<dependency> 
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId> 
			<version>${servletapi-version}</version> 
		</dependency>

		<dependency>
			<groupId>org.glassfish.jersey.containers</groupId>
			<artifactId>jersey-container-servlet-core</artifactId>
			<version>${jersey2-version}</version>
		</dependency>
		<dependency>
			<groupId>org.glassfish.jersey.media</groupId>
			<artifactId>jersey-media-multipart</artifactId>
			<version>${jersey2-version}</version>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.datatype</groupId>
			<artifactId>jackson-datatype-jsr310</artifactId>
			<version>${jackson-version}</version>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.jaxrs</groupId>
			<artifactId>jackson-jaxrs-json-provider</artifactId>
			<version>${jackson-version}</version>
		</dependency>
	</dependencies>



	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.1</version>
				<configuration>
					<generatedSourcesDirectory>src/main/generated</generatedSourcesDirectory>
				</configuration>
			</plugin>

			<plugin>
				<groupId>org.openapitools</groupId>
				<artifactId>openapi-generator-maven-plugin</artifactId>
				<version>4.2.3</version>
				<executions>
					<execution>
						<goals>
							<goal>generate</goal>
						</goals>
						<configuration>
							<inputSpec>${project.basedir}/src/main/resources/api2.yaml</inputSpec>
							<output>${project.basedir}</output>
							<generatorName>jaxrs-jersey</generatorName>

							<configOptions>
								<generatePom>true</generatePom>
								<dateLibrary>java8</dateLibrary>
								<java8>true</java8>
								<library>jersey2</library>

								<sourceFolder>src/main/generated</sourceFolder>
								<implFolder>src/main/java</implFolder>

								<apiPackage>de.test.openapi.server</apiPackage>
								<invokerPackage>de.test.openapi.server.invoker</invokerPackage>
								<modelPackage>de.test.openapi.server.model</modelPackage>
							</configOptions>
							<generateSupportingFiles>true</generateSupportingFiles>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>
</project> 

Steps to reproduce

run maven compile

Start with the api2.yaml reproduction and the jaxrs-jersey generator configuration shown in the issue, then run maven compile. Trace the generated model reference for the oneOf response and the ApiResponse annotation for the 5XX response. Done means the generated Java code compiles for both cases without the missing class or invalid integer annotation.