MINOR: Various Java cleanups in core (#14561)

Reviewers: Josep Prat <josep.prat@aiven.io>

core/src/main/java/kafka/log/remote/RemoteLogManager.java

@@ -155,13 +155,12 @@ public class RemoteLogManager implements Closeable {
     // topic ids that are received on leadership changes, this map is cleared on stop partitions
     private final ConcurrentMap<TopicPartition, Uuid> topicIdByPartitionMap = new ConcurrentHashMap<>();
     private final String clusterId;
+    private final KafkaMetricsGroup metricsGroup = new KafkaMetricsGroup(this.getClass());
 
     // The endpoint for remote log metadata manager to connect to
     private Optional<EndPoint> endpoint = Optional.empty();
     private boolean closed = false;
 
-    private KafkaMetricsGroup metricsGroup = new KafkaMetricsGroup(this.getClass());
-
     /**
      * Creates RemoteLogManager instance with the given arguments.
      *
@@ -230,7 +229,6 @@ public class RemoteLogManager implements Closeable {
         }
     }
 
-    @SuppressWarnings("removal")
     RemoteStorageManager createRemoteStorageManager() {
         return java.security.AccessController.doPrivileged(new PrivilegedAction<RemoteStorageManager>() {
             private final String classPath = rlmConfig.remoteStorageManagerClassPath();
@@ -253,7 +251,6 @@ public class RemoteLogManager implements Closeable {
         remoteLogStorageManager.configure(rsmProps);
     }
 
-    @SuppressWarnings("removal")
     RemoteLogMetadataManager createRemoteLogMetadataManager() {
         return java.security.AccessController.doPrivileged(new PrivilegedAction<RemoteLogMetadataManager>() {
             private final String classPath = rlmConfig.remoteLogMetadataManagerClassPath();

core/src/main/java/kafka/server/ReplicaFetcherTierStateMachine.java

@@ -69,8 +69,8 @@ import static org.apache.kafka.storage.internals.log.LogStartOffsetIncrementReas
 public class ReplicaFetcherTierStateMachine implements TierStateMachine {
     private static final Logger log = LoggerFactory.getLogger(ReplicaFetcherTierStateMachine.class);
 
-    private LeaderEndPoint leader;
-    private ReplicaManager replicaMgr;
+    private final LeaderEndPoint leader;
+    private final ReplicaManager replicaMgr;
 
     public ReplicaFetcherTierStateMachine(LeaderEndPoint leader,
                                           ReplicaManager replicaMgr) {

core/src/main/java/kafka/server/logger/RuntimeLoggerManager.java

@@ -142,7 +142,7 @@ public class RuntimeLoggerManager {
                         " operation is not allowed for the " + BROKER_LOGGER + " resource");
                 default:
                     throw new InvalidRequestException("Unknown operation type " +
-                        (int) op.configOperation() + " is not alowed for the " +
+                        (int) op.configOperation() + " is not allowed for the " +
                         BROKER_LOGGER + " resource");
             }
         });

core/src/test/java/kafka/log/remote/RemoteLogManagerTest.java

@@ -661,12 +661,12 @@ public class RemoteLogManagerTest {
     }
 
     private double yammerMetricValue(String name) {
-        Gauge<Double> guage = (Gauge) KafkaYammerMetrics.defaultRegistry().allMetrics().entrySet().stream()
+        Gauge<Double> gauge = (Gauge) KafkaYammerMetrics.defaultRegistry().allMetrics().entrySet().stream()
                 .filter(e -> e.getKey().getMBeanName().contains(name))
                 .findFirst()
                 .get()
                 .getValue();
-        return guage.value();
+        return gauge.value();
     }
 
     @Test
@@ -885,7 +885,7 @@ public class RemoteLogManagerTest {
                 public RemoteStorageManager createRemoteStorageManager() {
                     return rsmManager;
                 }
-            };
+            }
         ) {
             assertEquals(rsmManager, remoteLogManager.storageManager());
         }
@@ -1057,12 +1057,12 @@ public class RemoteLogManagerTest {
         txnIdxFile.createNewFile();
         when(remoteStorageManager.fetchIndex(any(RemoteLogSegmentMetadata.class), any(IndexType.class)))
                 .thenAnswer(ans -> {
-                    RemoteLogSegmentMetadata metadata = ans.<RemoteLogSegmentMetadata>getArgument(0);
-                    IndexType indexType = ans.<IndexType>getArgument(1);
+                    RemoteLogSegmentMetadata metadata = ans.getArgument(0);
+                    IndexType indexType = ans.getArgument(1);
                     int maxEntries = (int) (metadata.endOffset() - metadata.startOffset());
-                    OffsetIndex offsetIdx = new OffsetIndex(new File(tpDir, String.valueOf(metadata.startOffset()) + UnifiedLog.IndexFileSuffix()),
+                    OffsetIndex offsetIdx = new OffsetIndex(new File(tpDir, metadata.startOffset() + UnifiedLog.IndexFileSuffix()),
                             metadata.startOffset(), maxEntries * 8);
-                    TimeIndex timeIdx = new TimeIndex(new File(tpDir, String.valueOf(metadata.startOffset()) + UnifiedLog.TimeIndexFileSuffix()),
+                    TimeIndex timeIdx = new TimeIndex(new File(tpDir, metadata.startOffset() + UnifiedLog.TimeIndexFileSuffix()),
                             metadata.startOffset(), maxEntries * 12);
                     switch (indexType) {
                         case OFFSET:
@@ -1241,7 +1241,7 @@ public class RemoteLogManagerTest {
                 segmentEpochs5), logEndOffset, leaderEpochToStartOffset));
 
         // Test whether any of the epoch's is not with in the leader epoch chain.
-        TreeMap<Integer, Long> segmentEpochs6 = new TreeMap<Integer, Long>();
+        TreeMap<Integer, Long> segmentEpochs6 = new TreeMap<>();
         segmentEpochs6.put(5, 55L);
         segmentEpochs6.put(6, 60L); // epoch 6 exists here but it is missing in leaderEpochToStartOffset
         segmentEpochs6.put(7, 70L);
@@ -1834,7 +1834,7 @@ public class RemoteLogManagerTest {
             }
 
             // This is the key scenario that we are testing here
-            RecordBatch findFirstBatch(RemoteLogInputStream remoteLogInputStream, long offset) throws IOException {
+            RecordBatch findFirstBatch(RemoteLogInputStream remoteLogInputStream, long offset) {
                 return null;
             }
         }) {
@@ -1900,7 +1900,7 @@ public class RemoteLogManagerTest {
                 return 1;
             }
 
-            RecordBatch findFirstBatch(RemoteLogInputStream remoteLogInputStream, long offset) throws IOException {
+            RecordBatch findFirstBatch(RemoteLogInputStream remoteLogInputStream, long offset) {
                 when(firstBatch.sizeInBytes()).thenReturn(recordBatchSizeInBytes);
                 doNothing().when(firstBatch).writeTo(capture.capture());
                 return firstBatch;

core/src/test/java/kafka/test/server/BootstrapControllersIntegrationTest.java

@@ -111,7 +111,7 @@ public class BootstrapControllersIntegrationTest {
     }
 
     @Test
-    public void testPutBrokersInBootstrapControllersConfig() throws Exception {
+    public void testPutBrokersInBootstrapControllersConfig() {
         Properties properties = cluster.clientProperties();
         properties.put(BOOTSTRAP_CONTROLLERS_CONFIG, properties.getProperty(BOOTSTRAP_SERVERS_CONFIG));
         properties.remove(BOOTSTRAP_SERVERS_CONFIG);
@@ -127,7 +127,7 @@ public class BootstrapControllersIntegrationTest {
 
     @Disabled
     @Test
-    public void testPutControllersInBootstrapBrokersConfig() throws Exception {
+    public void testPutControllersInBootstrapBrokersConfig() {
         Properties properties = cluster.clientProperties();
         properties.put(BOOTSTRAP_SERVERS_CONFIG, bootstrapControllerString);
         try (Admin admin = Admin.create(properties)) {
@@ -169,7 +169,7 @@ public class BootstrapControllersIntegrationTest {
 
     @ParameterizedTest
     @ValueSource(booleans = {false, true})
-    public void testUpdateFeatures(boolean usingBootstrapControllers) throws Exception {
+    public void testUpdateFeatures(boolean usingBootstrapControllers) {
         try (Admin admin = Admin.create(adminProperties(usingBootstrapControllers))) {
             UpdateFeaturesResult result = admin.updateFeatures(Collections.singletonMap("foo.bar.feature",
                 new FeatureUpdate((short) 1, FeatureUpdate.UpgradeType.UPGRADE)),
@@ -196,7 +196,7 @@ public class BootstrapControllersIntegrationTest {
     }
 
     @Test
-    public void testUsingBootstrapControllersOnUnsupportedAdminApi() throws Exception {
+    public void testUsingBootstrapControllersOnUnsupportedAdminApi() {
         try (Admin admin = Admin.create(adminProperties(true))) {
             ListOffsetsResult result = admin.listOffsets(Collections.singletonMap(
                     new TopicPartition("foo", 0), OffsetSpec.earliest()));