chore(java-sdk): generate unknown value default cases for enums (#178)

Author: rubenhoenle

openapi-generator-config-java.yml

@@ -1,5 +1,6 @@
 templateDir: templates/java
 additionalProperties:
+  enumUnknownDefaultCase: true
   artifactUrl: https://github.com/stackitcloud/stackit-sdk-java
   developerName: STACKIT Developer Tools
   developerEmail: developer-tools@stackit.cloud
@@ -11,4 +12,4 @@ additionalProperties:
   licenseUrl: http://www.apache.org/licenses/
   scmConnection: scm:git@github.com:stackitcloud/stackit-sdk-java.git
   scmDeveloperConnection: scm:git@github.com:stackitcloud/stackit-sdk-java.git
-  scmUrl: https://github.com/stackitcloud/stackit-sdk-java
+  scmUrl: https://github.com/stackitcloud/stackit-sdk-java