PlantUML entities with inheritance have their own fields rendered (!12475) · Merge requests · OpenAPI Tools / openapi-generator

Created by: trreeves

Previously, any models with an 'allOf' property referencing a 'non inline' model would not have have fields included for the class/entity.

Now a model/entity has all fields included that are not specified by a non-inline 'allOf' model.

The problem this PR addresses is described in #12473. This issue also describes a QA test that can be performed.

An additional unit test has been added in this PR.

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Run the following to build the project and update samples:
```
./mvnw clean package 
./bin/generate-samples.sh
./bin/utils/export_docs_generators.sh
```
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