[BUG] DefaultCodegen.handleMethodResponse: importMappings vs. importMapping

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

DefaultCodegen.handleMethodResponse: importMappings parameter is never used: the class level importMapping is used instead...

https://github.com/OpenAPITools/openapi-generator/blob/eb3d6d2f1616bdba503c145d2349f798f85325f7/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java#L3531-L3536

openapi-generator version

5.0.1

Suggest a fix

Schema responseSchema = unaliasSchema(ModelUtils.getSchemaFromResponse(methodResponse), importMappings);

Open modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java around lines 3531-3536 and inspect how handleMethodResponse uses importMappings and importMapping. Done means the method uses the importMappings parameter, matching the suggested fix; the issue does not name a test to run.