[BUG] kotlin-spring generator resolves invalid package for imports form importMap

Created by: michael-wirth

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

kotlin-spring generator resolves invalid package name when using importMappings.

<configuration>
  <apiPackage>com.example.api</apiPackage>
  <importMappings>Problem=org.zalando.problem.Problem</importMappings>
</configuration>                    

resolves to: import com.example.model.org.zalando.problem.Problem;instead ofimport org.zalando.problem.Problem;`

The generation of the Java Spring version with the same api.yml works correctly.

openapi-generator version

4.2.3

OpenAPI declaration file content or url

# API-first development with OpenAPI
# This file will be used at compile time to generate Spring-MVC endpoint stubs using openapi-generator
openapi: '3.0.3'

info:
  title: demo
  version: 1.0.0

servers:
  - url: http://localhost:8080/api
    description: Local server

tags:
  - name: Account

paths:
  /accounts:
    get:
      tags:
        - Account
      operationId: listAccounts
      responses:
        '200':
          description: List of all available accounts
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Account'
        '404':
          $ref: '#/components/responses/Problem'
  /error:
    get:
      tags:
        - Account
      operationId: error
      responses:
        '200':
          $ref: '#/components/responses/Problem'

components:
  schemas:
    Account:
      type: object
      properties:
        id:
          description: Konto Laufnummer
          type: integer
          format: int64
        accountOwnerId:
          description: Kundennummer
          type: string
          maxLength: 12
        accountNumber:
          description: Kontonummer
          type: string
          maxLength: 20

  responses:
    Problem:
      description: error occurred - see status code and problem object for more information.
      content:
        'application/problem+json':
          schema:
            $ref: 'https://opensource.zalando.com/problem/schema.yaml#/Problem'
          example:
            url: https://zalando.com/problem/not-found
            title: Resource not found
            status: 404
            detail: index.html not found
            instance: /account/not-found

Generation Details

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
        <kotlin.version>1.3.72</kotlin.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jdk8</artifactId>
        </dependency>
        <dependency>
            <groupId>org.zalando</groupId>
            <artifactId>problem-spring-web-starter</artifactId>
            <version>0.25.2</version>
        </dependency>
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-kotlin</artifactId>
            <version>1.4.3</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>

            <plugin>
                <!--
                    Plugin that provides API-first development using openapi-generator to
                    generate Spring-MVC endpoint stubs at compile time from an OpenAPI definition file
                -->
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>4.2.3</version>
                <executions>
                    <execution>
                        <id>generate-kotlin-spring</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <apiPackage>com.example.api</apiPackage>
                            <generateApiTests>false</generateApiTests>
                            <generateSupportingFiles>false</generateSupportingFiles>
                            <generatorName>kotlin-spring</generatorName>
                            <importMappings>Problem=org.zalando.problem.Problem</importMappings>
                            <inputSpec>${project.basedir}/src/main/resources/api.yml</inputSpec>
                            <modelPackage>com.example.model</modelPackage>
                            <skipValidateSpec>false</skipValidateSpec>
                            <configOptions>
                                <basePackage>com.example</basePackage>
                                <exceptionHandler>false</exceptionHandler>
                                <enumPropertyNaming>UPPERCASE</enumPropertyNaming>
                                <interfaceOnly>false</interfaceOnly>
                                <serviceInterface>true</serviceInterface>
                                <sourceFolder>src/main/kotlin</sourceFolder>
                                <title>${project.artifactId}</title>
                            </configOptions>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Steps to reproduce

• save pom.xml
• save api.yml and save to src/main/resources/api.yml
• run mvn install

Related issues/PRs

Suggest a fix

Apply same logic as for the AbstractJavaCodeGen

   @Override
    protected boolean needToImport(String type) {
        return super.needToImport(type) && !type.contains(".");
    }

Alternative fix is to provide 2 import mappings. One to map the entity to the actual class name and another to prevent that the API package is used as prefix.

  
<importMappings>Problem=org.zalando.problem.Problem,org.zalando.problem.Problem=org.zalando.problem.Problem</importMappings>