Ver 3.0.0-rc1 generates code with missing imports when using enum

Description

Using Maven, I try to generate an API and classes in Java for my API. I use an enum and the generated code is missing these imports:
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonValue;

It has correctly imported:
import com.fasterxml.jackson.annotation.JsonProperty;

Swagger-codegen version

3.0.0-rc1
via Maven

Swagger declaration file content or url

---
swagger: '2.0'

################################################################################
#                              API Information                                 #
################################################################################
info:
  version: 1.0.0
  title: My API
  description: My test API.
  contact:
    url: http://undefined.undefined
    email: undefined@undefined.undefined

################################################################################
#                  Host, Base Path, Schemes and Content Types                  #
################################################################################
host: my-api

basePath: /my/api/v1.0.0
schemes:
  - http
produces:
  - application/json
consumes:
  - application/json

################################################################################
#                                    Paths                                     #
################################################################################

paths:
  '/consenttemplate':
    post:
      parameters:
        - name: body
          in: body
          required: true
          schema:
            $ref: '#/definitions/MyAPI'
      responses:
        200:
          schema:
           $ref: '#/definitions/MyAPI'

################################################################################
#                                 Definitions                                  #
################################################################################
definitions:
 MyAPI:
    type: object
    properties:
      uuid:
        type: string
      MyAPIState:
        type: string
        enum: [ DRAFT, APPROVED, ACTIVE, EXPIRED, CLOSED ]

Command line used for generation

mvn install
using this pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>dk.myapi</groupId>
  <artifactId>my-api</artifactId>
  <packaging>jar</packaging>
  <name>my-api</name>
  <version>1.0.0</version>
  <build>
  <plugins>
	<plugin>
		<groupId>io.swagger</groupId>
		<artifactId>swagger-codegen-maven-plugin</artifactId>
		<version>3.0.0-rc1</version>
		<executions>
        <execution>
            <goals>
                <goal>generate</goal>
            </goals>
			<phase>generate-sources</phase>
            <configuration>
                <language>jaxrs-spec</language>
				<inputSpec>my-api.yaml</inputSpec>
				<output>generated-sources</output>
                <typeMappings>
					<typeMapping>DateTime=Instant</typeMapping>
                </typeMappings>
                <importMappings>
					<importMapping>Instant=java.time.Instant</importMapping>
                </importMappings>
                <configOptions>
					<apiPackage>dk.myapi.common</apiPackage>
                    <modelPackage>dk.myapi.common.model</modelPackage>
                    <sourceFolder>src/java/main</sourceFolder>
    			    <interfaceOnly>true</interfaceOnly>
                    <generatePom>false</generatePom>
                    <java8>true</java8>
					<DuseBeanValidation>true</DuseBeanValidation>
                </configOptions>
				<configHelp></configHelp>
            </configuration>
        </execution>
		</executions>
	</plugin>	
 
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.1.0</version>
            </plugin>
            <plugin>
                <artifactId>maven-failsafe-plugin</artifactId>
                <version>2.6</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>integration-test</goal>
                            <goal>verify</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>build-helper-maven-plugin</artifactId>
                <version>1.9.1</version>
                <executions>
                    <execution>
                        <id>add-source</id>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>add-source</goal>
                        </goals>
                        <configuration>
                            <sources>
                                <source>
                                src/main/java</source>
                            </sources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
    </plugins>
  </build>
  <dependencies>
   <dependency>
     <groupId>com.fasterxml.jackson.core</groupId>
     <artifactId>jackson-annotations</artifactId>
     <version>2.9.6</version>
     <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.ws.rs</groupId>
      <artifactId>javax.ws.rs-api</artifactId>
      <version>2.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>io.swagger</groupId>
      <artifactId>swagger-annotations</artifactId>
      <scope>provided</scope>
      <version>1.5.21</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>${junit-version}</version>
      <scope>test</scope>
    </dependency>
    <!-- Bean Validation API support -->
    <dependency>
        <groupId>javax.validation</groupId>
        <artifactId>validation-api</artifactId>
        <version>1.1.0.Final</version>
        <scope>provided</scope>
    </dependency>
  </dependencies>
  <properties>
    <junit-version>4.8.1</junit-version>
  </properties>
</project>

Steps to reproduce

Save the attached yaml file as my-api.yaml and the pom-file as pom.xml in the same directory.
With Maven 3.5.0 on the PATH and Java 1.8.0_102 run:
mvn install

This fails with:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.6.1:compile (default-compile) on project my-api: Compilation failure: Compilation failure:
[ERROR] /C:/Users/me/generated-sources/src/java/main/io/swagger/model/MyAPI.java:[39,6] cannot find symbol
[ERROR]   symbol:   class JsonValue
[ERROR]   location: class io.swagger.model.MyAPI.MyAPIStateEnum
[ERROR] /C:/Users/me/generated-sources/src/java/main/io/swagger/model/MyAPI.java:[44,6] cannot find symbol
[ERROR]   symbol:   class JsonCreator
[ERROR]   location: class io.swagger.model.MyAPI.MyAPIStateEnum

When inspecting the file referred in the error message, it is possible to see that two annotations are used but not imported. There also is a lot of blank lines in the section which contains imports, which is a bit suspecious.

Workaround

1. Have a step that generates the sources
2. Have a script insert the missing imports
3. Run mvn install without generating new sources.

Reproduce the failure with my-api.yaml and pom.xml by running mvn install, then inspect the generated-sources/src/java/main/io/swagger/model/MyAPI.java imports and enum annotations. Done means the generated Java source includes JsonCreator and JsonValue imports and Maven compilation succeeds without the workaround.