<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>3.3.4</version>
    <executions>
        ...
    </executions>
</plugin>

<executions>
    <execution>
        <goals>
            <goal>generate</goal>
        </goals>
        <configuration>
            ...
        </configuration>
    </execution>
</executions>

<configuration>
    <inputSpec>
        ${project.basedir}/src/main/resources/api.yml
    </inputSpec>
    <generatorName>spring</generatorName>
    <configOptions>
        <sourceFolder>src/gen/java/main</sourceFolder>
        <interfaceOnly>true</interfaceOnly>
    </configOptions>
    <modelPackage>bzh.zomzog.apifirst.domain</modelPackage>
    <apiPackage>bzh.zomzog.apifirst.api</apiPackage>
    <generateSupportingFiles>true</generateSupportingFiles>
</configuration>

@RestController
public class PoniesController implements PoniesApi {

    @Override
    public ResponseEntity<Pony> getOne(String ponyId) {
        Pony pony = new Pony();
        pony.setId( "1" );
        pony.setName( "Rainbow dash" );
        pony.setColor( Pony.ColorEnum.RAINBOW );
        return ResponseEntity.ok( pony );
    }
}

<configuration>
    <inputSpec>
        ${project.basedir}/src/main/resources/api.yml
    </inputSpec>
    <generatorName>java</generatorName>
    <library>feign</library>
    <configOptions>
        <sourceFolder>src/gen/java/main</sourceFolder>
    </configOptions>
    <modelPackage>bzh.zomzog.prez.apifirst.domain</modelPackage>
    <apiPackage>bzh.zomzog.prez.apifirst.client.api</apiPackage>
    <generateSupportingFiles>true</generateSupportingFiles>
</configuration>

ApiClient apiClient = new ApiClient();
apiClient.setBasePath("http://localhost:8080");
Pony one = apiClient.buildClient(DefaultApi.class).getOne("1");

<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-jdk8</artifactId>
</dependency>
<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-processor</artifactId>
    <scope>provided</scope>
</dependency>

@Data
public class MyPony {

    private long id;
    private String name;
    private String color;
    private LocalDateTime createdAt;
    private String hiddenField;
}

@Mapper
public abstract class MyPonyMapper {

    public abstract MyPony map(Pony pony);
}

public LocalDateTime map(Long l) {
    return LocalDateTime.ofEpochSecond(l, 0, ZoneOffset.UTC);
}

@Mapper(componentModel = "spring",
        injectionStrategy = InjectionStrategy.CONSTRUCTOR,
        uses = NativeMapper.class)

@Mapping(target = "id", ignore = true)
public abstract MyPony update(Pony pony, @MappingTarget MyPony myPony);

@Builder
@Data
public class MyPony {