[BUG][JAVA-WIREMOCK] improper escaping of example responses

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, conversion of example responses to strings can lead to uncompilable output due to improper escaping.

openapi-generator version

latest master

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  version: 1.0.0
  title: OpenAPI Petstore
paths:
  /:
    get:
      responses:
        '200':
          description: successful operation
          content:
            application/json:
              schema:
                type: object
                properties:
                  dummyProp:
                    type: string
                    example: '"' # this causes problems

Compiling the generated output results in

[ERROR] src/main/java/org/openapitools/mockserver/api/DefaultApiMockServer.java:[39,40] illegal character: '\'

Generation Details

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

Related issues/PRs

originally discovered in https://github.com/OpenAPITools/openapi-generator/pull/17614

possibly related issues: https://github.com/OpenAPITools/openapi-generator/issues/3140, https://github.com/OpenAPITools/openapi-generator/issues/1691

Start with the java-wiremock generator and reproduce the issue using the supplied OpenAPI 3.0.3 specification, then compile its generated output. Trace conversion of the example response containing a quote and verify that the generated Java source escapes it correctly and compiles without the reported illegal-character error.