[BUG] Duplicate methods/fields generated

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

Duplicate fields and methods are being generated when generating JAX-RS spec server

When generating Java server code using the jaxrs-spec generator, model classes are generated with duplicate fields, methods, constructors, etc. I'm not positive, but I believe it may be due to the fact that the OpenAPI spec I'm generating off of contains $ref declarations.

openapi-generator version

5.4.0

OpenAPI declaration file content or url

The OpenAPI spec in question is here:

https://github.com/TheGeekPharaoh/asc4j/blob/main/src/main/resources/enhanced_app_store_connect_api_1.8_openapi.json

Generation Details

openapi-generator generate -i openapi.json
--api-package net.odyssi.asc4j.jaxrs
-g jaxrs-spec
--model-package net.odyssi.asc4j.model
--additional-properties=booleanGetterPrefix=is,dateLibrary=java8,openApiNullable=false,serializableModel=true,hideGenerationTimestamp=true,generateBuilders=true,sourceFolder=src/main/java,interfaceOnly=true,useSwaggerAnnotations=false

Steps to reproduce

Running the above command generates the malformed Java output

Start by running the provided openapi-generator command with the linked OpenAPI declaration and inspect the generated jaxrs-spec Java model classes. Trace how the referenced schemas produce fields, methods, and constructors, then verify that each generated member appears only once in the output.