[BUG][JavaSpring] Enum default value is only set if defined inline in schema

[ajdergute]

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? (3.3.4)
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

Depending if an enum is specified inline or not a the specified default value is assigned (or not). If defined inline (first case) a default value is assigned, as expected. If the enum is referenced via $ref, then 'null' is assigned, which should be changed.

openapi-generator version

As far as i know it's not a regression and I use OpenAPI Generator Version 3.2.3 and 3.3.4.

OpenAPI declaration file content or url

in both cases:

paths:
 /testenum:
 post:
 requestBody:
 content:
 application/json:
 schema:
 $ref: '#/components/schemas/TestObject'

works:

components:
 schemas:
 TestObject:
 type: object
 properties:
 myEnum:
 type: string
 default: FIRSTVALUE
 enum:
 - FIRSTVALUE
 - SECONDVALUE

and produces:

public class TestObjectDto {
 @JsonProperty("myEnum")
 private MyEnumEnum myEnum = MyEnumEnum.FIRSTVALUE;
}

doesn't work:

components:
 schemas:
 TestObject:
 type: object
 properties:
 myEnum:
 $ref: '#/components/schemas/MyEnum'
...
 MyEnum:
 type: string
 default: FIRSTVALUE
 enum:
 - FIRSTVALUE
 - SECONDVALUE

and produces:

public class TestObjectDto {
 @JsonProperty("myEnum")
 private MyEnumDto myEnum = null;
}

Command line used for generation

I used the maven generator plugin as follows:

 <plugin>
 <groupId>org.openapitools</groupId>
 <artifactId>openapi-generator-maven-plugin</artifactId>
 <version>3.3.4</version>
 <executions>
 <execution>
 <goals>
 <goal>generate</goal>
 </goals>
 <phase>generate-sources</phase>
 <configuration>
 <inputSpec>src/main/resources/swagger/api.yaml</inputSpec>
 <generatorName>spring</generatorName>
 <invokerPackage>${project.groupId}.service</invokerPackage>
 <apiPackage>${project.groupId}.service.api</apiPackage>
 <modelPackage>${project.groupId}.service.model</modelPackage>
 <modelNameSuffix>Dto</modelNameSuffix>
 <configOptions>
 <sourceFolder>src/main/java</sourceFolder>
 <library>spring-boot</library>
 <java8>true</java8>
 <dateLibrary>java8</dateLibrary>
 <useTags>true</useTags>
 <interfaceOnly>true</interfaceOnly>
 <delegatePattern>true</delegatePattern>
 <swaggerDocketConfig>false</swaggerDocketConfig>
 <configPackage>${project.groupId}.config</configPackage>
 </configOptions>
 </configuration>
 </execution>
 </executions>
 </plugin>

Steps to reproduce

Create an enum as described and see if default value is assigned.

Related issues/PRs

Suggest a fix

The expected behaviour in second case should be an default value assigment of the enum class like so:
private MyEnumDto myEnum = MyEnumDto.FIRSTVALUE;

[jmini]

Thank you for opening this issue!

I think this is the same issue as in #1927, toDefaultValue in AbstractJavaCodegen needs to unalias the schema.

[jmini]

I have pushed #2001 to solve this issue.

[jmini]

PR #2001 was merged, can you try with 4.0.0-SNAPSHOT and let us a comment here?

I am closing this issue. please reopen if you need anything.

[ajdergute]

Thank's a lot for this superfast bug fix. I tried it today with 4.0.0-beta2 and it works.

[jmini]

Some follow up is requested: see #2127

[tek08]

I think this issue has re-emerged, at least on python generated code? Fwiw, I'm usually using 4.3.1, but have also tried 5.0.0, for the sake of debugging, and found the same issue occurring.