Flowable Swagger json generates errors on swagger editor and when using swagger-codegen

I am using a SpringBoot app, with Flowable 6.2.1 .
Also using springfox-swagger2 to generate the Flowable Swagger.
Using swagger-codegen-cli 2.3.1

When displaying the generated swagger file (full swagger, with all Flowable endpoints) in Swagger editor, there are errors such as :

Semantic error at paths./runtime/process-instances/{processInstanceId}.get.parameters.0
Path parameters must have ‘required: true’. You can always create another path/operation without this parameter to get the same behaviour.
Jump to line 171
Schema error at paths[’/runtime/process-instances/{processInstanceId}’].get.parameters[0]
should NOT have additional properties additionalProperty: type, allowEmptyValue, name, in, description, required
Jump to line 171

When running swagger codegen to generate java client based on the swagger, I get these errors:

[main] WARN io.swagger.codegen.DefaultCodegen - Error obtaining the datatype from RefProperty:io.swagger.models.properties.RefProperty@286a7413. Datatype default to Object
[main] ERROR io.swagger.codegen.DefaultCodegen - null
java.lang.NullPointerException
at io.swagger.models.properties.RefProperty.get$ref(RefProperty.java:52)
at io.swagger.codegen.DefaultCodegen.getSwaggerType(DefaultCodegen.java:1150)
at io.swagger.codegen.languages.AbstractJavaCodegen.getSwaggerType(AbstractJavaCodegen.java:813)
at io.swagger.codegen.DefaultCodegen.fromProperty(DefaultCodegen.java:1781)
at io.swagger.codegen.DefaultCodegen.fromParameter(DefaultCodegen.java:2506)
at io.swagger.codegen.DefaultCodegen.fromOperation(DefaultCodegen.java:2213)
at io.swagger.codegen.languages.AbstractJavaCodegen.fromOperation(AbstractJavaCodegen.java:1057)
at io.swagger.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:881)
at io.swagger.codegen.DefaultGenerator.processPaths(DefaultGenerator.java:810)
at io.swagger.codegen.DefaultGenerator.generateApis(DefaultGenerator.java:431)
at io.swagger.codegen.DefaultGenerator.generate(DefaultGenerator.java:746)
at io.swagger.codegen.cmd.Generate.run(Generate.java:285)
at io.swagger.codegen.SwaggerCodegen.main(SwaggerCodegen.java:35)

Tried multiple versions of springfox-swagger2: 2.7.0, 2.8.0, 2.9.0 - same error.
Tried multiple Swagger editor versions - 3.1.4, 3.5.2 - same error.

Has anyone encountered this? I am unable to generate the client, so say I overcome this by invoking the API without a client, but I am afraid the errors indicate the swagger itself was generated badly.

Hi.

Would it be an option to use the swagger spec files we generate with Maven as a starting point?
You can have a look at the Flowable REST app.

(and use the Maven Swagger profile)

Regards,

Yvo