[BUG] Generator breaks on empty properties fields in components.

[davegarred]

Bug Report Checklist

• [X] Have you provided a full/minimal spec to reproduce the issue?
• [X] Have you validated the input using an OpenAPI validator (example)?
• [X] Have you tested with the latest master to confirm the issue still exists?
• [X] Have you searched for related issues/PRs?
• [X] What's the actual output vs expected output?

Description

Generator breaks on empty properties fields in components.

openapi-generator version

7.2.0-SNAPSHOT commit: 0d2a01611c8350b596a2b883964da2589e7baa93

OpenAPI declaration file content or url

The Discord API contains multiple empty properties which break in this tool but are valid. I've pushed up a simpler version taken taken from that.

Generation Details

Attempt to generate a client from a spec that includes a schema with property that is empty. E.g.,

"components": {
  "schemas": {
    "GithubWebhook": {
      "type": "object",
      "properties": {
        "pull_request": {}
      }
    }
  }
}

A NullPointerException is produced.

Exception: null
    at org.openapitools.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:1269)
    at org.openapitools.codegen.DefaultGenerator.processPaths(DefaultGenerator.java:1163)
    at org.openapitools.codegen.DefaultGenerator.generateApis(DefaultGenerator.java:609)
    at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:994)
    at org.openapitools.codegen.cmd.Generate.execute(Generate.java:519)
    at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
    at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)
Caused by: java.lang.NullPointerException
    at org.openapitools.codegen.examples.ExampleGenerator.resolvePropertyToExample(ExampleGenerator.java:228)
    at org.openapitools.codegen.examples.ExampleGenerator.resolveModelToExample(ExampleGenerator.java:352)
    at org.openapitools.codegen.examples.ExampleGenerator.resolvePropertyToExample(ExampleGenerator.java:311)
    at org.openapitools.codegen.examples.ExampleGenerator.resolveModelToExample(ExampleGenerator.java:352)
    at org.openapitools.codegen.examples.ExampleGenerator.generate(ExampleGenerator.java:159)
    at org.openapitools.codegen.DefaultCodegen.fromOperation(DefaultCodegen.java:4673)
    at org.openapitools.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:1237)
    ... 6 more

Steps to reproduce

Generate using the cli tool (any language).

docker run --rm -v ./:/local \
  openapitools/openapi-generator-cli \
  generate \
  -g rust \
  -o /local/output_directory \
  -i /local/openapi.json

Related issues/PRs

None found yet.

Suggest a fix

Edit: https://github.com/OpenAPITools/openapi-generator/pull/17173/files

[wing328]

thanks for reporting the issue.

I've filed https://github.com/OpenAPITools/openapi-generator/issues/17172 to address the NPE in example generator.

Will file another PR later to better support any type in 3.1 spec.

[wing328]

merged the fix to the master. please pull the latest master to give it a try.