[BUG][JAVA] Generated java code with generateAliasAsModel.set(true) not compiling

Description

given schema with

(...)
    ProviderDetails:
      type: object
      additionalProperties:
        type: string
      example:
        awsRegion: us-east-1
(...)        
    Database:
      type: object
      properties:
        providerDetails:
          $ref: '#/components/schemas/ProviderDetails'
(...)

openapi-generator used :
gradle plugin
id("org.openapi.generator") version "6.4.0"

generator : spring

Java code generated

@Schema(name = "ProviderDetails")
@Generated(value = "org.openapitools.codegen.languages.SpringCodegen")
public class ProviderDetails extends HashMap<String, String> {
(...)
}

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen")
public class Database {


  @JsonProperty("providerDetails")
  private ProviderDetails providerDetails = new HashMap<>();
  (...)
}

ProviderDetails providerDetails = new HashMap<>();
does not compile
I would expect either

private ProviderDetails providerDetails;
or
private ProviderDetails providerDetails = new ProviderDetails;

Is there a fix or workaround that can be used (updated mustache template) ?

Reproduce the issue with the provided schema, the Spring generator, and the Gradle plugin using generateAliasAsModel.set(true). Inspect the Spring generator templates responsible for Database and ProviderDetails initialization, then verify that the generated Java compiles and uses a valid ProviderDetails initialization or no initialization.