[BUG] Incorrect handling of octet stream for java 11 native

Description

If the type of the response is not JSON or primitive type but octet-stream, then the generated code handles it incorrectly.

The generated code will treat "File" as any other type and try to convert it.

  HttpResponse<InputStream> localVarResponse = memberVarHttpClient.send(
      localVarRequestBuilder.build(),
      HttpResponse.BodyHandlers.ofInputStream());
  if (localVarResponse.statusCode()/ 100 != 2) {
    throw new ApiException(localVarResponse.statusCode(),
        "filesUuidDownloadGet call received non-success response",
        localVarResponse.headers(),
        localVarResponse.body() == null ? null : new String(localVarResponse.body().readAllBytes()));
  }

openapi-generator version

4.1.0

Suggest a fix

The file or input stream should be passed as input parameter to where the respose should be written.

Reproduce the Java 11 native client generation for an octet-stream response and inspect the generated response-handling code shown in the issue. Confirm that the completed behavior passes the file or input stream to the requested output destination instead of treating File as a value to convert.