[BUG] Failed at unknown property

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

I am using openapi-generator-maven-plugin to generate the client jar of my application A. The client jar is introduced as a dependency of application B. Application B is calling the API of A at runtime time.
At some point, a new property onlineState was added to the DeviceDto, which caused application B to fail when trying to get the device.

Here is the stack.

Caused by: java.lang.IllegalArgumentException: The field `onlineState` in the JSON string is not defined in the `DeviceDto` properties. JSON: {\"serialNumber\":\"002\",\"onlineState\":\"OFFLINE\"}
    at package.name.DeviceDto.validateJsonElement(DeviceDto.java:148)
    at package.name.DeviceDto$CustomTypeAdapterFactory$1.read(DeviceDto.java:178)
    at package.name.DeviceDto$CustomTypeAdapterFactory$1.read(DeviceDto.java:168)
    at com.google.gson.TypeAdapter$1.read(TypeAdapter.java:199)
    at com.google.gson.Gson.fromJson(Gson.java:932)
    at com.google.gson.Gson.fromJson(Gson.java:897)
    at com.google.gson.Gson.fromJson(Gson.java:846)
    at package.name.client.api.JSON.deserialize(JSON.java:156)
    at package.name.client.api.ApiClient.deserialize(ApiClient.java:895)
    at package.name.client.api.ApiClient.handleResponse(ApiClient.java:1105)
    at package.name.client.api.ApiClient.execute(ApiClient.java:1029)
    at package.name.client.api.DeviceApi.getDeviceBySerialNumberWithHttpInfo(DeviceApi.java:693)
    at package.name.client.api.DeviceApi.getDeviceBySerialNumber(DeviceApi.java:673)
    

openapi-generator version

7.2.0

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

Start with the generated DeviceDto.java stack location, especially validateJsonElement, and reproduce against openapi-generator 7.2.0 using the missing OpenAPI declaration and generation steps, which the issue does not provide. Done means identifying and documenting the generator behavior for the added onlineState property with a minimal reproducible specification and regression coverage.