[BUG] String default wrong quotation

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

We use the maven plugin to create our models and interfaces in spring boot.
I wanted to set an optional header parameter to a default value used on the server side. However, I can not define the string correctly. The output is always masked incorrectly with extra double quotes.

openapi-generator version

org.openapitools openapi-generator-maven-plugin 3.3.4

OpenAPI declaration file content or url

components:
    parameters:
        XConsumerId:
            in: header
            name: x-consumer-id
            description: 'filled by gateway'
            required: false
            schema:
                type: string
                default: "c1" # tried also c1 and 'c1' 
            example: c1

Generated code
@ApiParam(value = "filled by gateway" , defaultValue=""c1"") @RequestHeader(value="x-consumer-id", required=false) String xConsumerId

"" of defaultValue is not correct

Command line used for generation

Execute maven plugin

Steps to reproduce

Related issues/PRs

Suggest a fix

Start with Maven plugin generation using the supplied OpenAPI parameter declaration and compare the generated @ApiParam defaultValue with the expected c1. Done means the generated Spring Boot interface preserves c1 without extra double quotes; the issue names no source file or test.