[BUG][JAVA-WIREMOCK] response code ranges are not supported

[martin-mfg]

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In the java-wiremock generator, response codes like "4XX" lead to uncompilable output.
The spec says such response codes are valid.

example spec

openapi: 3.0.3
info:
  version: 1.0.0
  title: OpenAPI Petstore
paths:
  /:
    get:
      responses:
        4XX: # this causes problems
          description: client error

Compiling the generated output results in

[ERROR] src/main/java/org/openapitools/mockserver/api/DefaultApiMockServer.java:[17,30] ')' expected
[ERROR] src/main/java/org/openapitools/mockserver/api/DefaultApiMockServer.java:[17,32] ';' expected

openapi-generator version

latest master

Generation Details

use generator "java-wiremock", with no additional settings

Related issues/PRs

originally discovered in #17614