fix(java-sdk): allow additional properties in responses (#228)

relates to STACKITSDK-314

Author: marceljk

languages/java/openapi-generator-config.yml

@@ -6,6 +6,7 @@ additionalProperties:
   developerEmail: developer-tools@stackit.cloud
   developerOrganization: STACKIT
   developerOrganizationUrl: https://www.stackit.de
+  disallowAdditionalPropertiesIfNotPresent: false
   groupId: cloud.stackit.sdk
   hideGenerationTimestamp: true
   licenseName: Apache License 2.0