Fix unsupported DESCRIBE_CONFIGS (#939)

kafka-ui-api/src/main/java/com/provectus/kafka/ui/service/BrokerServiceImpl.java

@@ -7,8 +7,8 @@ import com.provectus.kafka.ui.model.ExtendedAdminClient;
 import com.provectus.kafka.ui.model.InternalBrokerConfig;
 import com.provectus.kafka.ui.model.KafkaCluster;
 import com.provectus.kafka.ui.util.ClusterUtil;
-import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -18,6 +18,7 @@ import org.apache.kafka.clients.admin.ConfigEntry;
 import org.apache.kafka.clients.admin.DescribeConfigsOptions;
 import org.apache.kafka.common.Node;
 import org.apache.kafka.common.config.ConfigResource;
+import org.apache.kafka.common.errors.UnsupportedVersionException;
 import org.springframework.stereotype.Service;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -39,11 +40,15 @@ public class BrokerServiceImpl implements BrokerService {
         .map(ExtendedAdminClient::getAdminClient)
         .flatMap(adminClient ->
             ClusterUtil.toMono(adminClient.describeConfigs(resources,
-                new DescribeConfigsOptions().includeSynonyms(true)).all())
-                .map(config -> config.entrySet().stream()
+                    new DescribeConfigsOptions().includeSynonyms(true)).all())
+                .map(config -> config.entrySet()
+                    .stream()
                     .collect(Collectors.toMap(
                         c -> Integer.valueOf(c.getKey().name()),
-                        c -> new ArrayList<>(c.getValue().entries())))));
+                        c -> List.copyOf(c.getValue().entries())
+                    ))
+                ))
+        .onErrorResume(UnsupportedVersionException.class, (e) -> Mono.just(new HashMap<>()));
   }
 
   private Mono<List<ConfigEntry>> loadBrokersConfig(