Output of snippet generator is broken

### Version report

Jenkins and plugins versions report:

```
Jenkins: 2.303.1
OS: Linux - 5.10.0-8-amd64
---
aws-credentials:1.32
```

- What Operating System are you using (both controller, and any agents involved in the problem)?

```
Linux
```

### Reproduction steps

- Go to the pipeline snippet generator
- Select `withCredentials`
- Select an AWS credential
- Hit "Generate pipeline script"

### Results

Expected result:

A nice pipeline like
```
withCredentials([[$class: 'AmazonWebServicesCredentialsBinding', credentialsId: 'foobar']]) {
// some block
}
```
or
```
withCredentials([aws(credentialsId: 'foobar')]) {
// some block
}
```
(as seen on https://www.jenkins.io/doc/pipeline/steps/credentials-binding/#withcredentials-bind-credentials-to-variables)

Actual result:


```
withCredentials([]) {
// some block
}
```

Start with the Jenkins pipeline snippet generator and reproduce the issue by selecting `withCredentials` and an AWS credential. Compare the generated output with the documented `withCredentials` examples and verify that the result contains a usable AWS binding and credential ID rather than an object placeholder.

Written by the indexing model from the issue text.