[BUG][JAVA][SPRING] Problem with URI encoding with RestTemplate in ApiClient (version 5.4.0)

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

Hi, in my projects I use the 5.4.0 version of the plugin. I have a problem when the path variables have special characters like the spaces.

In particular, I recieve this Exception:

Caused by: java.net.URISyntaxException: Illegal character in path at index 109

The bug is caused by ApiClient for RestTemplate, in this point (https://github.com/OpenAPITools/openapi-generator/blob/v5.4.0/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache#L625-L632):

public String expandPath(String pathTemplate, Map<String, Object> variables) {
    // disable default URL encoding
    DefaultUriBuilderFactory uriBuilderFactory = new DefaultUriBuilderFactory();
    uriBuilderFactory.setEncodingMode(DefaultUriBuilderFactory.EncodingMode.NONE);
    final RestTemplate restTemplate = new RestTemplate();
    restTemplate.setUriTemplateHandler(uriBuilderFactory);
        
}

That piece of code invalids the encoding mode of RestTemplate passed of client (and the default encoding mode).

The master branch fixed it (https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache#L610-L612):

public String expandPath(String pathTemplate, Map<String, Object> variables) {
        return restTemplate.getUriTemplateHandler().expand(pathTemplate, variables).toString();
}

but I can't update the plugin from version 5 to version 6 (for too many impacts). Is it possible a 5.4.1 version for this fix?
(I woudl like to not create a custom APiClient template to fix it).

openapi-generator version

Version 5.4.0

Steps to reproduce

For example, with this path:

String requestId = "PREPARE_ANALOG_DOMICILE.  OBJECT_HAWE-DAYD-LVRK-202302-G-1.INDEX_0.SENTATTEMPTMADE_0";
 String path = "/try-channel-private/v1/b2b/try-deliveries-prepare/{requestId}"
                .replace("{requestId}", requestId);

I received the Exception: Caused by: java.net.URISyntaxException: Illegal character in path...

Suggest a fix

The fix like in master branch.

Start in modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache at the expandPath implementation referenced in the issue, and compare it with the master-branch version linked there. Reproduce the failure using the supplied requestId containing spaces; done means RestTemplate's configured URI encoding is preserved and the path no longer raises URISyntaxException.