[BUG][openapi-generator-gradle-plugin] Property value not used

[kierans]

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

When using Gradle Properties in strings the value of the property isn't used eg:

Successfully generated code to property(class java.lang.String, property(class java.lang.String, fixed(class java.lang.String, /Users/kieran/Projects/project/build/generated/openapi)))

openapi-generator version

plugins {
    id 'org.openapi.generator' version '4.3.0'
}

Command line used for generation

$ ./gradlew openApiGenerate

Steps to reproduce

1. Create a fresh Gradle project following the README
2. Pick an API spec. If none handy, the Petstore will do
3. Run command to generate code
4. Read console output

Related issues/PRs

None that I can find

Suggest a fix

Where properties are used in strings, or in console output, the value should be get() first