public interface AlterConfigPolicy extends Configurable, AutoCloseable {

    class RequestMetadata {

        private final ConfigResource resource;
        private final Map<String, String> proposedConfigs;
        private final List<String> proposedConfigsToDelete; 
        private final Map<String, String> existingConfigsresultingConfigs;

        public RequestMetadata(ConfigResource resource, Map<String, String> proposedConfigs) {
            this.resource = resource;
            this.proposedConfigs = proposedConfigs;
            this.existingConfigsresultingConfigs = Collections.emptyMap();
            this.proposedConfigsToDelete = Collections.emptyList();
        }

        public RequestMetadata(ConfigResource resource, Map<String, String> proposedConfigs, List<String> proposedConfigsToDelete, Map<String, String> existingConfigsresultingConfigs) {
            this.resource = resource;
            this.proposedConfigs = proposedConfigs;
            this.existingConfigsresultingConfigs = existingConfigsresultingConfigs;
            this.proposedConfigsToDelete = proposedConfigsToDelete;
        }

		// ...

        public List<String> proposedConfigsToDelete() {
            return proposedConfigsToDelete;
        } 

        public Map<String, String> existingConfigsresultingConfigs() {
            return existingConfigsresultingConfigs;
        }

    // ...

    void validate(RequestMetadata requestMetadata) throws PolicyViolationException;
}