BE: Fix sonar code smells (#3971)

Co-authored-by: Roman Zabaluev <rzabaluev@provectus.com>

kafka-ui-api/src/main/java/com/provectus/kafka/ui/config/CorsGlobalConfiguration.java

@@ -7,8 +7,6 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
-import org.springframework.web.reactive.config.CorsRegistry;
-import org.springframework.web.reactive.config.WebFluxConfigurer;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebFilter;
 import org.springframework.web.server.WebFilterChain;

kafka-ui-api/src/main/java/com/provectus/kafka/ui/config/WebclientProperties.java

@@ -1,7 +1,6 @@
 package com.provectus.kafka.ui.config;
 
 import com.provectus.kafka.ui.exception.ValidationException;
-import java.beans.Transient;
 import javax.annotation.PostConstruct;
 import lombok.Data;
 import org.springframework.boot.context.properties.ConfigurationProperties;

kafka-ui-api/src/main/java/com/provectus/kafka/ui/config/auth/AuthenticatedUser.java

@@ -1,7 +1,6 @@
 package com.provectus.kafka.ui.config.auth;
 
 import java.util.Collection;
-import lombok.Value;
 
 public record AuthenticatedUser(String principal, Collection<String> groups) {
 

kafka-ui-api/src/main/java/com/provectus/kafka/ui/config/auth/RbacOAuth2User.java

@@ -2,7 +2,6 @@ package com.provectus.kafka.ui.config.auth;
 
 import java.util.Collection;
 import java.util.Map;
-import lombok.Value;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.oauth2.core.user.OAuth2User;
 

kafka-ui-api/src/main/java/com/provectus/kafka/ui/config/auth/RbacOidcUser.java

@@ -2,7 +2,6 @@ package com.provectus.kafka.ui.config.auth;
 
 import java.util.Collection;
 import java.util.Map;
-import lombok.Value;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.oauth2.core.oidc.OidcIdToken;
 import org.springframework.security.oauth2.core.oidc.OidcUserInfo;

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/AccessController.java

@@ -13,7 +13,6 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
-import java.util.stream.Collectors;
 import javax.annotation.Nullable;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -38,7 +37,7 @@ public class AccessController implements AuthorizationApi {
             .filter(role -> user.groups().contains(role.getName()))
             .map(role -> mapPermissions(role.getPermissions(), role.getClusters()))
             .flatMap(Collection::stream)
-            .collect(Collectors.toList())
+            .toList()
         )
         .switchIfEmpty(Mono.just(Collections.emptyList()));
 
@@ -70,10 +69,10 @@ public class AccessController implements AuthorizationApi {
               .map(String::toUpperCase)
               .map(this::mapAction)
               .filter(Objects::nonNull)
-              .collect(Collectors.toList()));
+              .toList());
           return dto;
         })
-        .collect(Collectors.toList());
+        .toList();
   }
 
   @Nullable

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/BrokersController.java

@@ -26,6 +26,8 @@ import reactor.core.publisher.Mono;
 @RequiredArgsConstructor
 @Slf4j
 public class BrokersController extends AbstractController implements BrokersApi {
+  private static final String BROKER_ID = "brokerId";
+
   private final BrokerService brokerService;
   private final ClusterMapper clusterMapper;
 
@@ -89,7 +91,7 @@ public class BrokersController extends AbstractController implements BrokersApi
         .cluster(clusterName)
         .clusterConfigActions(ClusterConfigAction.VIEW)
         .operationName("getBrokerConfig")
-        .operationParams(Map.of("brokerId", id))
+        .operationParams(Map.of(BROKER_ID, id))
         .build();
 
     return validateAccess(context).thenReturn(
@@ -108,7 +110,7 @@ public class BrokersController extends AbstractController implements BrokersApi
         .cluster(clusterName)
         .clusterConfigActions(ClusterConfigAction.VIEW, ClusterConfigAction.EDIT)
         .operationName("updateBrokerTopicPartitionLogDir")
-        .operationParams(Map.of("brokerId", id))
+        .operationParams(Map.of(BROKER_ID, id))
         .build();
 
     return validateAccess(context).then(
@@ -128,7 +130,7 @@ public class BrokersController extends AbstractController implements BrokersApi
         .cluster(clusterName)
         .clusterConfigActions(ClusterConfigAction.VIEW, ClusterConfigAction.EDIT)
         .operationName("updateBrokerConfigByName")
-        .operationParams(Map.of("brokerId", id))
+        .operationParams(Map.of(BROKER_ID, id))
         .build();
 
     return validateAccess(context).then(

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/ConsumerGroupsController.java

@@ -22,7 +22,6 @@ import com.provectus.kafka.ui.service.OffsetsResetService;
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.Supplier;
-import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Value;
@@ -200,7 +199,7 @@ public class ConsumerGroupsController extends AbstractController implements Cons
         .consumerGroups(consumerGroupConsumerGroupsPage.consumerGroups()
             .stream()
             .map(ConsumerGroupMapper::toDto)
-            .collect(Collectors.toList()));
+            .toList());
   }
 
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/KafkaConnectController.java

@@ -36,6 +36,7 @@ import reactor.core.publisher.Mono;
 public class KafkaConnectController extends AbstractController implements KafkaConnectApi {
   private static final Set<ConnectorActionDTO> RESTART_ACTIONS
       = Set.of(RESTART, RESTART_FAILED_TASKS, RESTART_ALL_TASKS);
+  private static final String CONNECTOR_NAME = "connectorName";
 
   private final KafkaConnectService kafkaConnectService;
 
@@ -112,7 +113,7 @@ public class KafkaConnectController extends AbstractController implements KafkaC
         .connect(connectName)
         .connectActions(ConnectAction.VIEW, ConnectAction.EDIT)
         .operationName("deleteConnector")
-        .operationParams(Map.of("connectorName", connectName))
+        .operationParams(Map.of(CONNECTOR_NAME, connectName))
         .build();
 
     return validateAccess(context).then(
@@ -180,7 +181,7 @@ public class KafkaConnectController extends AbstractController implements KafkaC
         .connect(connectName)
         .connectActions(ConnectAction.VIEW, ConnectAction.EDIT)
         .operationName("setConnectorConfig")
-        .operationParams(Map.of("connectorName", connectorName))
+        .operationParams(Map.of(CONNECTOR_NAME, connectorName))
         .build();
 
     return validateAccess(context).then(
@@ -207,7 +208,7 @@ public class KafkaConnectController extends AbstractController implements KafkaC
         .connect(connectName)
         .connectActions(connectActions)
         .operationName("updateConnectorState")
-        .operationParams(Map.of("connectorName", connectorName))
+        .operationParams(Map.of(CONNECTOR_NAME, connectorName))
         .build();
 
     return validateAccess(context).then(
@@ -227,7 +228,7 @@ public class KafkaConnectController extends AbstractController implements KafkaC
         .connect(connectName)
         .connectActions(ConnectAction.VIEW)
         .operationName("getConnectorTasks")
-        .operationParams(Map.of("connectorName", connectorName))
+        .operationParams(Map.of(CONNECTOR_NAME, connectorName))
         .build();
 
     return validateAccess(context).thenReturn(
@@ -247,7 +248,7 @@ public class KafkaConnectController extends AbstractController implements KafkaC
         .connect(connectName)
         .connectActions(ConnectAction.VIEW, ConnectAction.RESTART)
         .operationName("restartConnectorTask")
-        .operationParams(Map.of("connectorName", connectorName))
+        .operationParams(Map.of(CONNECTOR_NAME, connectorName))
         .build();
 
     return validateAccess(context).then(

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/SchemasController.java

@@ -15,7 +15,6 @@ import com.provectus.kafka.ui.model.rbac.permission.SchemaAction;
 import com.provectus.kafka.ui.service.SchemaRegistryService;
 import java.util.List;
 import java.util.Map;
-import java.util.stream.Collectors;
 import javax.validation.Valid;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -235,7 +234,7 @@ public class SchemasController extends AbstractController implements SchemasApi
           List<String> subjectsToRender = filteredSubjects.stream()
               .skip(subjectToSkip)
               .limit(pageSize)
-              .collect(Collectors.toList());
+              .toList();
           return schemaRegistryService.getAllLatestVersionSchemas(getCluster(clusterName), subjectsToRender)
               .map(subjs -> subjs.stream().map(kafkaSrMapper::toDto).toList())
               .map(subjs -> new SchemaSubjectsResponseDTO().pageCount(totalPages).schemas(subjs));

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/TopicsController.java

@@ -143,7 +143,7 @@ public class TopicsController extends AbstractController implements TopicsApi {
             .map(lst -> lst.stream()
                 .map(InternalTopicConfig::from)
                 .map(clusterMapper::toTopicConfig)
-                .collect(toList()))
+                .toList())
             .map(Flux::fromIterable)
             .map(ResponseEntity::ok)
     ).doOnEach(sig -> audit(context, sig));
@@ -207,7 +207,7 @@ public class TopicsController extends AbstractController implements TopicsApi {
           return topicsService.loadTopics(getCluster(clusterName), topicsPage)
               .map(topicsToRender ->
                   new TopicsResponseDTO()
-                      .topics(topicsToRender.stream().map(clusterMapper::toTopic).collect(toList()))
+                      .topics(topicsToRender.stream().map(clusterMapper::toTopic).toList())
                       .pageCount(totalPages));
         })
         .map(ResponseEntity::ok)

kafka-ui-api/src/main/java/com/provectus/kafka/ui/emitter/OffsetsInfo.java

@@ -5,7 +5,6 @@ import java.util.Collection;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
-import java.util.stream.Collectors;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.mutable.MutableLong;
@@ -28,7 +27,7 @@ class OffsetsInfo {
     this(consumer,
         consumer.partitionsFor(topic).stream()
             .map(pi -> new TopicPartition(topic, pi.partition()))
-            .collect(Collectors.toList())
+            .toList()
     );
   }
 

kafka-ui-api/src/main/java/com/provectus/kafka/ui/exception/GlobalErrorWebExceptionHandler.java

@@ -106,7 +106,7 @@ public class GlobalErrorWebExceptionHandler extends AbstractErrorWebExceptionHan
           err.setFieldName(e.getKey());
           err.setRestrictions(List.copyOf(e.getValue()));
           return err;
-        }).collect(Collectors.toList());
+        }).toList();
 
     var message = fieldsErrors.isEmpty()
         ? exception.getMessage()

kafka-ui-api/src/main/java/com/provectus/kafka/ui/mapper/ClusterMapper.java

@@ -33,7 +33,6 @@ import com.provectus.kafka.ui.model.TopicDetailsDTO;
 import com.provectus.kafka.ui.service.metrics.RawMetric;
 import java.util.List;
 import java.util.Map;
-import java.util.stream.Collectors;
 import org.apache.kafka.clients.admin.ConfigEntry;
 import org.apache.kafka.common.acl.AccessControlEntry;
 import org.apache.kafka.common.acl.AclBinding;
@@ -54,7 +53,7 @@ public interface ClusterMapper {
 
   default ClusterMetricsDTO toClusterMetrics(Metrics metrics) {
     return new ClusterMetricsDTO()
-        .items(metrics.getSummarizedMetrics().map(this::convert).collect(Collectors.toList()));
+        .items(metrics.getSummarizedMetrics().map(this::convert).toList());
   }
 
   private MetricDTO convert(RawMetric rawMetric) {
@@ -66,7 +65,7 @@ public interface ClusterMapper {
 
   default BrokerMetricsDTO toBrokerMetrics(List<RawMetric> metrics) {
     return new BrokerMetricsDTO()
-        .metrics(metrics.stream().map(this::convert).collect(Collectors.toList()));
+        .metrics(metrics.stream().map(this::convert).toList());
   }
 
   @Mapping(target = "isSensitive", source = "sensitive")
@@ -107,7 +106,7 @@ public interface ClusterMapper {
   List<ClusterDTO.FeaturesEnum> toFeaturesEnum(List<ClusterFeature> features);
 
   default List<PartitionDTO> map(Map<Integer, InternalPartition> map) {
-    return map.values().stream().map(this::toPartition).collect(Collectors.toList());
+    return map.values().stream().map(this::toPartition).toList();
   }
 
   default BrokerDiskUsageDTO map(Integer id, InternalBrokerDiskUsage internalBrokerDiskUsage) {

kafka-ui-api/src/main/java/com/provectus/kafka/ui/mapper/DescribeLogDirsMapper.java

@@ -21,7 +21,7 @@ public class DescribeLogDirsMapper {
     return logDirsInfo.entrySet().stream().map(
         mapEntry -> mapEntry.getValue().entrySet().stream()
             .map(e -> toBrokerLogDirs(mapEntry.getKey(), e.getKey(), e.getValue()))
-            .collect(Collectors.toList())
+            .toList()
     ).flatMap(Collection::stream).collect(Collectors.toList());
   }
 
@@ -35,7 +35,7 @@ public class DescribeLogDirsMapper {
     var topics = logDirInfo.replicaInfos.entrySet().stream()
         .collect(Collectors.groupingBy(e -> e.getKey().topic())).entrySet().stream()
         .map(e -> toTopicLogDirs(broker, e.getKey(), e.getValue()))
-        .collect(Collectors.toList());
+        .toList();
     result.setTopics(topics);
     return result;
   }
@@ -48,7 +48,7 @@ public class DescribeLogDirsMapper {
     topic.setPartitions(
         partitions.stream().map(
             e -> topicPartitionLogDir(
-                broker, e.getKey().partition(), e.getValue())).collect(Collectors.toList())
+                broker, e.getKey().partition(), e.getValue())).toList()
     );
     return topic;
   }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/model/InternalLogDirStats.java

@@ -44,7 +44,7 @@ public class InternalLogDirStats {
                 topicMap.getValue().replicaInfos.entrySet().stream()
                     .map(e -> Tuples.of(b.getKey(), e.getKey(), e.getValue().size))
             )
-        ).collect(toList());
+        ).toList();
 
     partitionsStats = topicPartitions.stream().collect(
         groupingBy(

kafka-ui-api/src/main/java/com/provectus/kafka/ui/model/rbac/AccessContext.java

@@ -52,6 +52,8 @@ public class AccessContext {
   }
 
   public static final class AccessContextBuilder {
+    private static final String ACTIONS_NOT_PRESENT = "actions not present";
+
     private Collection<ApplicationConfigAction> applicationConfigActions = Collections.emptySet();
     private String cluster;
     private Collection<ClusterConfigAction> clusterConfigActions = Collections.emptySet();
@@ -75,7 +77,7 @@ public class AccessContext {
     }
 
     public AccessContextBuilder applicationConfigActions(ApplicationConfigAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.applicationConfigActions = List.of(actions);
       return this;
     }
@@ -86,7 +88,7 @@ public class AccessContext {
     }
 
     public AccessContextBuilder clusterConfigActions(ClusterConfigAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.clusterConfigActions = List.of(actions);
       return this;
     }
@@ -97,7 +99,7 @@ public class AccessContext {
     }
 
     public AccessContextBuilder topicActions(TopicAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.topicActions = List.of(actions);
       return this;
     }
@@ -108,7 +110,7 @@ public class AccessContext {
     }
 
     public AccessContextBuilder consumerGroupActions(ConsumerGroupAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.consumerGroupActions = List.of(actions);
       return this;
     }
@@ -119,7 +121,7 @@ public class AccessContext {
     }
 
     public AccessContextBuilder connectActions(ConnectAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.connectActions = List.of(actions);
       return this;
     }
@@ -135,25 +137,25 @@ public class AccessContext {
     }
 
     public AccessContextBuilder schemaActions(SchemaAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.schemaActions = List.of(actions);
       return this;
     }
 
     public AccessContextBuilder ksqlActions(KsqlAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.ksqlActions = List.of(actions);
       return this;
     }
 
     public AccessContextBuilder aclActions(AclAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.aclActions = List.of(actions);
       return this;
     }
 
     public AccessContextBuilder auditActions(AuditAction... actions) {
-      Assert.isTrue(actions.length > 0, "actions not present");
+      Assert.isTrue(actions.length > 0, ACTIONS_NOT_PRESENT);
       this.auditActions = List.of(actions);
       return this;
     }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/serdes/builtin/Base64Serde.java

@@ -6,7 +6,6 @@ import com.provectus.kafka.ui.serdes.BuiltInSerde;
 import java.util.Base64;
 import java.util.Map;
 import java.util.Optional;
-import org.apache.kafka.common.header.Headers;
 
 public class Base64Serde implements BuiltInSerde {
 

kafka-ui-api/src/main/java/com/provectus/kafka/ui/serdes/builtin/ConsumerOffsetsSerde.java

@@ -28,6 +28,23 @@ public class ConsumerOffsetsSerde implements BuiltInSerde {
 
   private static final JsonMapper JSON_MAPPER = createMapper();
 
+  private static final String ASSIGNMENT = "assignment";
+  private static final String CLIENT_HOST = "client_host";
+  private static final String CLIENT_ID = "client_id";
+  private static final String COMMIT_TIMESTAMP = "commit_timestamp";
+  private static final String CURRENT_STATE_TIMESTAMP = "current_state_timestamp";
+  private static final String GENERATION = "generation";
+  private static final String LEADER = "leader";
+  private static final String MEMBERS = "members";
+  private static final String MEMBER_ID = "member_id";
+  private static final String METADATA = "metadata";
+  private static final String OFFSET = "offset";
+  private static final String PROTOCOL = "protocol";
+  private static final String PROTOCOL_TYPE = "protocol_type";
+  private static final String REBALANCE_TIMEOUT = "rebalance_timeout";
+  private static final String SESSION_TIMEOUT = "session_timeout";
+  private static final String SUBSCRIPTION = "subscription";
+
   public static final String TOPIC = "__consumer_offsets";
 
   public static String name() {
@@ -116,128 +133,128 @@ public class ConsumerOffsetsSerde implements BuiltInSerde {
   private Deserializer valueDeserializer() {
     final Schema commitOffsetSchemaV0 =
         new Schema(
-            new Field("offset", Type.INT64, ""),
-            new Field("metadata", Type.STRING, ""),
-            new Field("commit_timestamp", Type.INT64, "")
+            new Field(OFFSET, Type.INT64, ""),
+            new Field(METADATA, Type.STRING, ""),
+            new Field(COMMIT_TIMESTAMP, Type.INT64, "")
         );
 
     final Schema commitOffsetSchemaV1 =
         new Schema(
-            new Field("offset", Type.INT64, ""),
-            new Field("metadata", Type.STRING, ""),
-            new Field("commit_timestamp", Type.INT64, ""),
+            new Field(OFFSET, Type.INT64, ""),
+            new Field(METADATA, Type.STRING, ""),
+            new Field(COMMIT_TIMESTAMP, Type.INT64, ""),
             new Field("expire_timestamp", Type.INT64, "")
         );
 
     final Schema commitOffsetSchemaV2 =
         new Schema(
-            new Field("offset", Type.INT64, ""),
-            new Field("metadata", Type.STRING, ""),
-            new Field("commit_timestamp", Type.INT64, "")
+            new Field(OFFSET, Type.INT64, ""),
+            new Field(METADATA, Type.STRING, ""),
+            new Field(COMMIT_TIMESTAMP, Type.INT64, "")
         );
 
     final Schema commitOffsetSchemaV3 =
         new Schema(
-            new Field("offset", Type.INT64, ""),
+            new Field(OFFSET, Type.INT64, ""),
             new Field("leader_epoch", Type.INT32, ""),
-            new Field("metadata", Type.STRING, ""),
-            new Field("commit_timestamp", Type.INT64, "")
+            new Field(METADATA, Type.STRING, ""),
+            new Field(COMMIT_TIMESTAMP, Type.INT64, "")
         );
 
     final Schema commitOffsetSchemaV4 = new Schema(
-        new Field("offset", Type.INT64, ""),
+        new Field(OFFSET, Type.INT64, ""),
         new Field("leader_epoch", Type.INT32, ""),
-        new Field("metadata", Type.COMPACT_STRING, ""),
-        new Field("commit_timestamp", Type.INT64, ""),
+        new Field(METADATA, Type.COMPACT_STRING, ""),
+        new Field(COMMIT_TIMESTAMP, Type.INT64, ""),
         Field.TaggedFieldsSection.of()
     );
 
     final Schema metadataSchema0 =
         new Schema(
-            new Field("protocol_type", Type.STRING, ""),
-            new Field("generation", Type.INT32, ""),
-            new Field("protocol", Type.NULLABLE_STRING, ""),
-            new Field("leader", Type.NULLABLE_STRING, ""),
-            new Field("members", new ArrayOf(new Schema(
-                new Field("member_id", Type.STRING, ""),
-                new Field("client_id", Type.STRING, ""),
-                new Field("client_host", Type.STRING, ""),
-                new Field("session_timeout", Type.INT32, ""),
-                new Field("subscription", Type.BYTES, ""),
-                new Field("assignment", Type.BYTES, "")
+            new Field(PROTOCOL_TYPE, Type.STRING, ""),
+            new Field(GENERATION, Type.INT32, ""),
+            new Field(PROTOCOL, Type.NULLABLE_STRING, ""),
+            new Field(LEADER, Type.NULLABLE_STRING, ""),
+            new Field(MEMBERS, new ArrayOf(new Schema(
+                new Field(MEMBER_ID, Type.STRING, ""),
+                new Field(CLIENT_ID, Type.STRING, ""),
+                new Field(CLIENT_HOST, Type.STRING, ""),
+                new Field(SESSION_TIMEOUT, Type.INT32, ""),
+                new Field(SUBSCRIPTION, Type.BYTES, ""),
+                new Field(ASSIGNMENT, Type.BYTES, "")
             )), "")
         );
 
     final Schema metadataSchema1 =
         new Schema(
-            new Field("protocol_type", Type.STRING, ""),
-            new Field("generation", Type.INT32, ""),
-            new Field("protocol", Type.NULLABLE_STRING, ""),
-            new Field("leader", Type.NULLABLE_STRING, ""),
-            new Field("members", new ArrayOf(new Schema(
-                new Field("member_id", Type.STRING, ""),
-                new Field("client_id", Type.STRING, ""),
-                new Field("client_host", Type.STRING, ""),
-                new Field("rebalance_timeout", Type.INT32, ""),
-                new Field("session_timeout", Type.INT32, ""),
-                new Field("subscription", Type.BYTES, ""),
-                new Field("assignment", Type.BYTES, "")
+            new Field(PROTOCOL_TYPE, Type.STRING, ""),
+            new Field(GENERATION, Type.INT32, ""),
+            new Field(PROTOCOL, Type.NULLABLE_STRING, ""),
+            new Field(LEADER, Type.NULLABLE_STRING, ""),
+            new Field(MEMBERS, new ArrayOf(new Schema(
+                new Field(MEMBER_ID, Type.STRING, ""),
+                new Field(CLIENT_ID, Type.STRING, ""),
+                new Field(CLIENT_HOST, Type.STRING, ""),
+                new Field(REBALANCE_TIMEOUT, Type.INT32, ""),
+                new Field(SESSION_TIMEOUT, Type.INT32, ""),
+                new Field(SUBSCRIPTION, Type.BYTES, ""),
+                new Field(ASSIGNMENT, Type.BYTES, "")
             )), "")
         );
 
     final Schema metadataSchema2 =
         new Schema(
-            new Field("protocol_type", Type.STRING, ""),
-            new Field("generation", Type.INT32, ""),
-            new Field("protocol", Type.NULLABLE_STRING, ""),
-            new Field("leader", Type.NULLABLE_STRING, ""),
-            new Field("current_state_timestamp", Type.INT64, ""),
-            new Field("members", new ArrayOf(new Schema(
-                new Field("member_id", Type.STRING, ""),
-                new Field("client_id", Type.STRING, ""),
-                new Field("client_host", Type.STRING, ""),
-                new Field("rebalance_timeout", Type.INT32, ""),
-                new Field("session_timeout", Type.INT32, ""),
-                new Field("subscription", Type.BYTES, ""),
-                new Field("assignment", Type.BYTES, "")
+            new Field(PROTOCOL_TYPE, Type.STRING, ""),
+            new Field(GENERATION, Type.INT32, ""),
+            new Field(PROTOCOL, Type.NULLABLE_STRING, ""),
+            new Field(LEADER, Type.NULLABLE_STRING, ""),
+            new Field(CURRENT_STATE_TIMESTAMP, Type.INT64, ""),
+            new Field(MEMBERS, new ArrayOf(new Schema(
+                new Field(MEMBER_ID, Type.STRING, ""),
+                new Field(CLIENT_ID, Type.STRING, ""),
+                new Field(CLIENT_HOST, Type.STRING, ""),
+                new Field(REBALANCE_TIMEOUT, Type.INT32, ""),
+                new Field(SESSION_TIMEOUT, Type.INT32, ""),
+                new Field(SUBSCRIPTION, Type.BYTES, ""),
+                new Field(ASSIGNMENT, Type.BYTES, "")
             )), "")
         );
 
     final Schema metadataSchema3 =
         new Schema(
-            new Field("protocol_type", Type.STRING, ""),
-            new Field("generation", Type.INT32, ""),
-            new Field("protocol", Type.NULLABLE_STRING, ""),
-            new Field("leader", Type.NULLABLE_STRING, ""),
-            new Field("current_state_timestamp", Type.INT64, ""),
-            new Field("members", new ArrayOf(new Schema(
-                new Field("member_id", Type.STRING, ""),
+            new Field(PROTOCOL_TYPE, Type.STRING, ""),
+            new Field(GENERATION, Type.INT32, ""),
+            new Field(PROTOCOL, Type.NULLABLE_STRING, ""),
+            new Field(LEADER, Type.NULLABLE_STRING, ""),
+            new Field(CURRENT_STATE_TIMESTAMP, Type.INT64, ""),
+            new Field(MEMBERS, new ArrayOf(new Schema(
+                new Field(MEMBER_ID, Type.STRING, ""),
                 new Field("group_instance_id", Type.NULLABLE_STRING, ""),
-                new Field("client_id", Type.STRING, ""),
-                new Field("client_host", Type.STRING, ""),
-                new Field("rebalance_timeout", Type.INT32, ""),
-                new Field("session_timeout", Type.INT32, ""),
-                new Field("subscription", Type.BYTES, ""),
-                new Field("assignment", Type.BYTES, "")
+                new Field(CLIENT_ID, Type.STRING, ""),
+                new Field(CLIENT_HOST, Type.STRING, ""),
+                new Field(REBALANCE_TIMEOUT, Type.INT32, ""),
+                new Field(SESSION_TIMEOUT, Type.INT32, ""),
+                new Field(SUBSCRIPTION, Type.BYTES, ""),
+                new Field(ASSIGNMENT, Type.BYTES, "")
             )), "")
         );
 
     final Schema metadataSchema4 =
         new Schema(
-            new Field("protocol_type", Type.COMPACT_STRING, ""),
-            new Field("generation", Type.INT32, ""),
-            new Field("protocol", Type.COMPACT_NULLABLE_STRING, ""),
-            new Field("leader", Type.COMPACT_NULLABLE_STRING, ""),
-            new Field("current_state_timestamp", Type.INT64, ""),
-            new Field("members", new CompactArrayOf(new Schema(
-                new Field("member_id", Type.COMPACT_STRING, ""),
+            new Field(PROTOCOL_TYPE, Type.COMPACT_STRING, ""),
+            new Field(GENERATION, Type.INT32, ""),
+            new Field(PROTOCOL, Type.COMPACT_NULLABLE_STRING, ""),
+            new Field(LEADER, Type.COMPACT_NULLABLE_STRING, ""),
+            new Field(CURRENT_STATE_TIMESTAMP, Type.INT64, ""),
+            new Field(MEMBERS, new CompactArrayOf(new Schema(
+                new Field(MEMBER_ID, Type.COMPACT_STRING, ""),
                 new Field("group_instance_id", Type.COMPACT_NULLABLE_STRING, ""),
-                new Field("client_id", Type.COMPACT_STRING, ""),
-                new Field("client_host", Type.COMPACT_STRING, ""),
-                new Field("rebalance_timeout", Type.INT32, ""),
-                new Field("session_timeout", Type.INT32, ""),
-                new Field("subscription", Type.COMPACT_BYTES, ""),
-                new Field("assignment", Type.COMPACT_BYTES, ""),
+                new Field(CLIENT_ID, Type.COMPACT_STRING, ""),
+                new Field(CLIENT_HOST, Type.COMPACT_STRING, ""),
+                new Field(REBALANCE_TIMEOUT, Type.INT32, ""),
+                new Field(SESSION_TIMEOUT, Type.INT32, ""),
+                new Field(SUBSCRIPTION, Type.COMPACT_BYTES, ""),
+                new Field(ASSIGNMENT, Type.COMPACT_BYTES, ""),
                 Field.TaggedFieldsSection.of()
             )), ""),
             Field.TaggedFieldsSection.of()
@@ -249,7 +266,7 @@ public class ConsumerOffsetsSerde implements BuiltInSerde {
       short version = bb.getShort();
       // ideally, we should distinguish if value is commit or metadata
       // by checking record's key, but our current serde structure doesn't allow that.
-      // so, we trying to parse into metadata first and after into commit msg
+      // so, we are trying to parse into metadata first and after into commit msg
       try {
         result = toJson(
             switch (version) {

kafka-ui-api/src/main/java/com/provectus/kafka/ui/serdes/builtin/Int32Serde.java

@@ -2,7 +2,6 @@ package com.provectus.kafka.ui.serdes.builtin;
 
 import com.google.common.primitives.Ints;
 import com.provectus.kafka.ui.serde.api.DeserializeResult;
-import com.provectus.kafka.ui.serde.api.PropertyResolver;
 import com.provectus.kafka.ui.serde.api.SchemaDescription;
 import com.provectus.kafka.ui.serdes.BuiltInSerde;
 import java.util.Map;

kafka-ui-api/src/main/java/com/provectus/kafka/ui/serdes/builtin/sr/SchemaRegistrySerde.java

@@ -43,6 +43,8 @@ public class SchemaRegistrySerde implements BuiltInSerde {
     return "SchemaRegistry";
   }
 
+  private static final String SCHEMA_REGISTRY = "schemaRegistry";
+
   private SchemaRegistryClient schemaRegistryClient;
   private List<String> schemaRegistryUrls;
   private String valueSchemaNameTemplate;
@@ -54,7 +56,7 @@ public class SchemaRegistrySerde implements BuiltInSerde {
   @Override
   public boolean canBeAutoConfigured(PropertyResolver kafkaClusterProperties,
                                      PropertyResolver globalProperties) {
-    return kafkaClusterProperties.getListProperty("schemaRegistry", String.class)
+    return kafkaClusterProperties.getListProperty(SCHEMA_REGISTRY, String.class)
         .filter(lst -> !lst.isEmpty())
         .isPresent();
   }
@@ -62,7 +64,7 @@ public class SchemaRegistrySerde implements BuiltInSerde {
   @Override
   public void autoConfigure(PropertyResolver kafkaClusterProperties,
                             PropertyResolver globalProperties) {
-    var urls = kafkaClusterProperties.getListProperty("schemaRegistry", String.class)
+    var urls = kafkaClusterProperties.getListProperty(SCHEMA_REGISTRY, String.class)
         .filter(lst -> !lst.isEmpty())
         .orElseThrow(() -> new ValidationException("No urls provided for schema registry"));
     configure(
@@ -88,7 +90,7 @@ public class SchemaRegistrySerde implements BuiltInSerde {
                         PropertyResolver kafkaClusterProperties,
                         PropertyResolver globalProperties) {
     var urls = serdeProperties.getListProperty("url", String.class)
-        .or(() -> kafkaClusterProperties.getListProperty("schemaRegistry", String.class))
+        .or(() -> kafkaClusterProperties.getListProperty(SCHEMA_REGISTRY, String.class))
         .filter(lst -> !lst.isEmpty())
         .orElseThrow(() -> new ValidationException("No urls provided for schema registry"));
     configure(

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

@@ -11,6 +11,9 @@ import org.apache.kafka.common.Node;
 
 class WellKnownMetrics {
 
+  private static final String BROKER_TOPIC_METRICS = "BrokerTopicMetrics";
+  private static final String FIFTEEN_MINUTE_RATE = "FifteenMinuteRate";
+
   // per broker
   final Map<Integer, BigDecimal> brokerBytesInFifteenMinuteRate = new HashMap<>();
   final Map<Integer, BigDecimal> brokerBytesOutFifteenMinuteRate = new HashMap<>();
@@ -36,15 +39,15 @@ class WellKnownMetrics {
     if (!brokerBytesInFifteenMinuteRate.containsKey(node.id())
         && rawMetric.labels().size() == 1
         && "BytesInPerSec".equalsIgnoreCase(rawMetric.labels().get("name"))
-        && containsIgnoreCase(name, "BrokerTopicMetrics")
-        && endsWithIgnoreCase(name, "FifteenMinuteRate")) {
+        && containsIgnoreCase(name, BROKER_TOPIC_METRICS)
+        && endsWithIgnoreCase(name, FIFTEEN_MINUTE_RATE)) {
       brokerBytesInFifteenMinuteRate.put(node.id(),  rawMetric.value());
     }
     if (!brokerBytesOutFifteenMinuteRate.containsKey(node.id())
         && rawMetric.labels().size() == 1
         && "BytesOutPerSec".equalsIgnoreCase(rawMetric.labels().get("name"))
-        && containsIgnoreCase(name, "BrokerTopicMetrics")
-        && endsWithIgnoreCase(name, "FifteenMinuteRate")) {
+        && containsIgnoreCase(name, BROKER_TOPIC_METRICS)
+        && endsWithIgnoreCase(name, FIFTEEN_MINUTE_RATE)) {
       brokerBytesOutFifteenMinuteRate.put(node.id(), rawMetric.value());
     }
   }
@@ -53,8 +56,8 @@ class WellKnownMetrics {
     String name = rawMetric.name();
     String topic = rawMetric.labels().get("topic");
     if (topic != null
-        && containsIgnoreCase(name, "BrokerTopicMetrics")
-        && endsWithIgnoreCase(name, "FifteenMinuteRate")) {
+        && containsIgnoreCase(name, BROKER_TOPIC_METRICS)
+        && endsWithIgnoreCase(name, FIFTEEN_MINUTE_RATE)) {
       String nameProperty = rawMetric.labels().get("name");
       if ("BytesInPerSec".equalsIgnoreCase(nameProperty)) {
         bytesInFifteenMinuteRate.compute(topic, (k, v) -> v == null ? rawMetric.value() : v.add(rawMetric.value()));

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

@@ -52,6 +52,7 @@ import reactor.core.publisher.Mono;
 public class AccessControlService {
 
   private static final String ACCESS_DENIED = "Access denied";
+  private static final String ACTIONS_ARE_EMPTY = "actions are empty";
 
   @Nullable
   private final InMemoryReactiveClientRegistrationRepository clientRegistrationRepository;
@@ -206,7 +207,7 @@ public class AccessControlService {
     if (context.getTopic() == null && context.getTopicActions().isEmpty()) {
       return true;
     }
-    Assert.isTrue(!context.getTopicActions().isEmpty(), "actions are empty");
+    Assert.isTrue(!context.getTopicActions().isEmpty(), ACTIONS_ARE_EMPTY);
 
     Set<String> requiredActions = context.getTopicActions()
         .stream()
@@ -243,7 +244,7 @@ public class AccessControlService {
     if (context.getConsumerGroup() == null && context.getConsumerGroupActions().isEmpty()) {
       return true;
     }
-    Assert.isTrue(!context.getConsumerGroupActions().isEmpty(), "actions are empty");
+    Assert.isTrue(!context.getConsumerGroupActions().isEmpty(), ACTIONS_ARE_EMPTY);
 
     Set<String> requiredActions = context.getConsumerGroupActions()
         .stream()
@@ -276,7 +277,7 @@ public class AccessControlService {
     if (context.getSchema() == null && context.getSchemaActions().isEmpty()) {
       return true;
     }
-    Assert.isTrue(!context.getSchemaActions().isEmpty(), "actions are empty");
+    Assert.isTrue(!context.getSchemaActions().isEmpty(), ACTIONS_ARE_EMPTY);
 
     Set<String> requiredActions = context.getSchemaActions()
         .stream()
@@ -309,7 +310,7 @@ public class AccessControlService {
     if (context.getConnect() == null && context.getConnectActions().isEmpty()) {
       return true;
     }
-    Assert.isTrue(!context.getConnectActions().isEmpty(), "actions are empty");
+    Assert.isTrue(!context.getConnectActions().isEmpty(), ACTIONS_ARE_EMPTY);
 
     Set<String> requiredActions = context.getConnectActions()
         .stream()

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/jsonschema/JsonAvroConversion.java

@@ -43,6 +43,8 @@ public class JsonAvroConversion {
 
   private static final JsonMapper MAPPER = new JsonMapper();
   private static final Schema NULL_SCHEMA = Schema.create(Schema.Type.NULL);
+  private static final String FORMAT = "format";
+  private static final String DATE_TIME = "date-time";
 
   // converts json into Object that is expected input for KafkaAvroSerializer
   // (with AVRO_USE_LOGICAL_TYPE_CONVERTERS flat enabled!)
@@ -347,7 +349,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("uuid"))))
+                Map.of(FORMAT, new TextNode("uuid"))))
     ),
 
     DECIMAL("decimal",
@@ -385,7 +387,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("date"))))
+                Map.of(FORMAT, new TextNode("date"))))
     ),
 
     TIME_MILLIS("time-millis",
@@ -406,7 +408,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("time"))))
+                Map.of(FORMAT, new TextNode("time"))))
     ),
 
     TIME_MICROS("time-micros",
@@ -427,7 +429,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("time"))))
+                Map.of(FORMAT, new TextNode("time"))))
     ),
 
     TIMESTAMP_MILLIS("timestamp-millis",
@@ -448,7 +450,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("date-time"))))
+                Map.of(FORMAT, new TextNode(DATE_TIME))))
     ),
 
     TIMESTAMP_MICROS("timestamp-micros",
@@ -473,7 +475,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("date-time"))))
+                Map.of(FORMAT, new TextNode(DATE_TIME))))
     ),
 
     LOCAL_TIMESTAMP_MILLIS("local-timestamp-millis",
@@ -491,7 +493,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("date-time"))))
+                Map.of(FORMAT, new TextNode(DATE_TIME))))
     ),
 
     LOCAL_TIMESTAMP_MICROS("local-timestamp-micros",
@@ -508,7 +510,7 @@ public class JsonAvroConversion {
         new SimpleFieldSchema(
             new SimpleJsonType(
                 JsonType.Type.STRING,
-                Map.of("format", new TextNode("date-time"))))
+                Map.of(FORMAT, new TextNode(DATE_TIME))))
     );
 
     private final String name;

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/jsonschema/ProtobufSchemaConverter.java

@@ -37,6 +37,9 @@ import reactor.util.function.Tuples;
 
 public class ProtobufSchemaConverter implements JsonSchemaConverter<Descriptors.Descriptor> {
 
+  private static final String MAXIMUM = "maximum";
+  private static final String MINIMUM = "minimum";
+
   private final Set<String> simpleTypesWrapperNames = Set.of(
       BoolValue.getDescriptor().getFullName(),
       Int32Value.getDescriptor().getFullName(),
@@ -156,15 +159,15 @@ public class ProtobufSchemaConverter implements JsonSchemaConverter<Descriptors.
       case INT32, FIXED32, SFIXED32, SINT32 -> new SimpleJsonType(
           JsonType.Type.INTEGER,
           Map.of(
-              "maximum", IntNode.valueOf(Integer.MAX_VALUE),
-              "minimum", IntNode.valueOf(Integer.MIN_VALUE)
+              MAXIMUM, IntNode.valueOf(Integer.MAX_VALUE),
+              MINIMUM, IntNode.valueOf(Integer.MIN_VALUE)
           )
       );
       case UINT32 -> new SimpleJsonType(
           JsonType.Type.INTEGER,
           Map.of(
-              "maximum", LongNode.valueOf(UnsignedInteger.MAX_VALUE.longValue()),
-              "minimum", IntNode.valueOf(0)
+              MAXIMUM, LongNode.valueOf(UnsignedInteger.MAX_VALUE.longValue()),
+              MINIMUM, IntNode.valueOf(0)
           )
       );
       //TODO: actually all *64 types will be printed with quotes (as strings),
@@ -173,15 +176,15 @@ public class ProtobufSchemaConverter implements JsonSchemaConverter<Descriptors.
       case INT64, FIXED64, SFIXED64, SINT64 -> new SimpleJsonType(
           JsonType.Type.INTEGER,
           Map.of(
-              "maximum", LongNode.valueOf(Long.MAX_VALUE),
-              "minimum", LongNode.valueOf(Long.MIN_VALUE)
+              MAXIMUM, LongNode.valueOf(Long.MAX_VALUE),
+              MINIMUM, LongNode.valueOf(Long.MIN_VALUE)
           )
       );
       case UINT64 -> new SimpleJsonType(
           JsonType.Type.INTEGER,
           Map.of(
-              "maximum", new BigIntegerNode(UnsignedLong.MAX_VALUE.bigIntegerValue()),
-              "minimum", LongNode.valueOf(0)
+              MAXIMUM, new BigIntegerNode(UnsignedLong.MAX_VALUE.bigIntegerValue()),
+              MINIMUM, LongNode.valueOf(0)
           )
       );
       case MESSAGE, GROUP -> new SimpleJsonType(JsonType.Type.OBJECT);

kafka-ui-e2e-checks/src/main/java/com/provectus/kafka/ui/models/Schema.java

@@ -10,25 +10,27 @@ import lombok.experimental.Accessors;
 @Accessors(chain = true)
 public class Schema {
 
+  private static final String USER_DIR = "user.dir";
+
   private String name, valuePath;
   private SchemaType type;
 
   public static Schema createSchemaAvro() {
     return new Schema().setName("schema_avro-" + randomAlphabetic(5))
         .setType(SchemaType.AVRO)
-        .setValuePath(System.getProperty("user.dir") + "/src/main/resources/testData/schemas/schema_avro_value.json");
+        .setValuePath(System.getProperty(USER_DIR) + "/src/main/resources/testData/schemas/schema_avro_value.json");
   }
 
   public static Schema createSchemaJson() {
     return new Schema().setName("schema_json-" + randomAlphabetic(5))
         .setType(SchemaType.JSON)
-        .setValuePath(System.getProperty("user.dir") + "/src/main/resources/testData/schemas/schema_json_Value.json");
+        .setValuePath(System.getProperty(USER_DIR) + "/src/main/resources/testData/schemas/schema_json_Value.json");
   }
 
   public static Schema createSchemaProtobuf() {
     return new Schema().setName("schema_protobuf-" + randomAlphabetic(5))
         .setType(SchemaType.PROTOBUF)
         .setValuePath(
-            System.getProperty("user.dir") + "/src/main/resources/testData/schemas/schema_protobuf_value.txt");
+            System.getProperty(USER_DIR) + "/src/main/resources/testData/schemas/schema_protobuf_value.txt");
   }
 }

kafka-ui-e2e-checks/src/main/java/com/provectus/kafka/ui/pages/topics/TopicCreateEditForm.java

@@ -19,6 +19,8 @@ import io.qameta.allure.Step;
 
 public class TopicCreateEditForm extends BasePage {
 
+  private static final String RETENTION_BYTES = "retentionBytes";
+
   protected SelenideElement timeToRetainField = $x("//input[@id='timeToRetain']");
   protected SelenideElement partitionsField = $x("//input[@name='partitions']");
   protected SelenideElement nameField = $(id("topicFormName"));
@@ -138,12 +140,12 @@ public class TopicCreateEditForm extends BasePage {
 
   @Step
   public TopicCreateEditForm selectRetentionBytes(String visibleValue) {
-    return selectFromDropDownByVisibleText("retentionBytes", visibleValue);
+    return selectFromDropDownByVisibleText(RETENTION_BYTES, visibleValue);
   }
 
   @Step
   public TopicCreateEditForm selectRetentionBytes(Long optionValue) {
-    return selectFromDropDownByOptionValue("retentionBytes", optionValue.toString());
+    return selectFromDropDownByOptionValue(RETENTION_BYTES, optionValue.toString());
   }
 
   @Step
@@ -202,7 +204,7 @@ public class TopicCreateEditForm extends BasePage {
 
   @Step
   public String getMaxSizeOnDisk() {
-    return new KafkaUiSelectElement("retentionBytes").getCurrentValue();
+    return new KafkaUiSelectElement(RETENTION_BYTES).getCurrentValue();
   }
 
   @Step