Bug Report Checklist

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

When generating code using openapi-generator-maven-plugin 6.3.0 with an array containing an object having anyOf (see provided example), the generated code is broken:

joiner.add(getArrayItems().get(i).toUrlQueryString(String.format("%sarrayItems%s%s", prefix, suffix,
          "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix))));

Cannot resolve method 'toUrlQueryString' in 'ArrayItem'

Without the anyOf in the OpenAPI yaml file, the code is correct.

openapi-generator version

Version 6.3.0, it worked fine in 6.2.1

OpenAPI declaration file content or url

https://gist.github.com/mvanglabbeek/30951b64448e74f8a8182e2f0b57e995

Generation Details

Via, openapi-generator-maven-plugin see https://gist.github.com/mvanglabbeek/30951b64448e74f8a8182e2f0b57e995

Steps to reproduce

Generate the code using the openapi-generator, using mvn 3.8.1

Related issues/PRs

#14178

Suggest a fix