[minor] Fix warnings in AbstractFetcher(Test)

flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/internals/AbstractFetcher.java

@@ -130,9 +130,11 @@ public abstract class AbstractFetcher<T, KPH> {
 	 */
 	private final MetricGroup consumerMetricGroup;
 
+	@SuppressWarnings("DeprecatedIsStillUsed")
 	@Deprecated
 	private final MetricGroup legacyCurrentOffsetsMetricGroup;
 
+	@SuppressWarnings("DeprecatedIsStillUsed")
 	@Deprecated
 	private final MetricGroup legacyCommittedOffsetsMetricGroup;
 
@@ -185,7 +187,7 @@ public abstract class AbstractFetcher<T, KPH> {
 				userCodeClassLoader);
 
 		// check that all seed partition states have a defined offset
-		for (KafkaTopicPartitionState partitionState : subscribedPartitionStates) {
+		for (KafkaTopicPartitionState<?> partitionState : subscribedPartitionStates) {
 			if (!partitionState.isOffsetDefined()) {
 				throw new IllegalArgumentException("The fetcher was assigned seed partitions with undefined initial offsets.");
 			}
@@ -204,7 +206,7 @@ public abstract class AbstractFetcher<T, KPH> {
 		// if we have periodic watermarks, kick off the interval scheduler
 		if (timestampWatermarkMode == PERIODIC_WATERMARKS) {
 			@SuppressWarnings("unchecked")
-			PeriodicWatermarkEmitter periodicEmitter = new PeriodicWatermarkEmitter(
+			PeriodicWatermarkEmitter<KPH> periodicEmitter = new PeriodicWatermarkEmitter(
 					subscribedPartitionStates,
 					sourceContext,
 					processingTimeProvider,
@@ -303,7 +305,7 @@ public abstract class AbstractFetcher<T, KPH> {
 		return offsets.entrySet()
 			.stream()
 			.filter(entry -> !KafkaTopicPartitionStateSentinel.isSentinel(entry.getValue()))
-			.collect(Collectors.toMap(entry -> entry.getKey(), entry -> entry.getValue()));
+			.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 	}
 
 	/**

flink-connectors/flink-connector-kafka-base/src/test/java/org/apache/flink/streaming/connectors/kafka/internals/AbstractFetcherTest.java

@@ -443,7 +443,7 @@ public class AbstractFetcherTest {
 	// ------------------------------------------------------------------------
 
 	private static final class TestFetcher<T> extends AbstractFetcher<T, Object> {
-		Optional<Map<KafkaTopicPartition, Long>> lastCommittedOffsets = Optional.empty();
+		Map<KafkaTopicPartition, Long> lastCommittedOffsets = null;
 
 		private final OneShotLatch fetchLoopWaitLatch;
 		private final OneShotLatch stateIterationBlockLatch;
@@ -499,7 +499,7 @@ public class AbstractFetcherTest {
 		@Override
 		public void runFetchLoop() throws Exception {
 			if (fetchLoopWaitLatch != null) {
-				for (KafkaTopicPartitionState ignored : subscribedPartitionStates()) {
+				for (KafkaTopicPartitionState<?> ignored : subscribedPartitionStates()) {
 					fetchLoopWaitLatch.trigger();
 					stateIterationBlockLatch.await();
 				}
@@ -521,13 +521,13 @@ public class AbstractFetcherTest {
 		@Override
 		protected void doCommitInternalOffsetsToKafka(
 				Map<KafkaTopicPartition, Long> offsets,
-				@Nonnull KafkaCommitCallback callback) throws Exception {
-			lastCommittedOffsets = Optional.of(offsets);
+				@Nonnull KafkaCommitCallback callback) {
+			lastCommittedOffsets = offsets;
 			callback.onSuccess();
 		}
 
 		public Optional<Map<KafkaTopicPartition, Long>> getLastCommittedOffsets() {
-			return lastCommittedOffsets;
+			return Optional.ofNullable(lastCommittedOffsets);
 		}
 	}
 
@@ -537,7 +537,7 @@ public class AbstractFetcherTest {
 			AbstractFetcher<T, KPH> fetcher,
 			T record,
 			KafkaTopicPartitionState<KPH> partitionState,
-			long offset) throws Exception {
+			long offset) {
 		ArrayDeque<T> recordQueue = new ArrayDeque<>();
 		recordQueue.add(record);
 
@@ -552,7 +552,7 @@ public class AbstractFetcherTest {
 			AbstractFetcher<T, KPH> fetcher,
 			List<T> records,
 			KafkaTopicPartitionState<KPH> partitionState,
-			long offset) throws Exception {
+			long offset) {
 		ArrayDeque<T> recordQueue = new ArrayDeque<>(records);
 
 		fetcher.emitRecordsWithTimestamps(
@@ -566,6 +566,7 @@ public class AbstractFetcherTest {
 		return new ArrayDeque<>();
 	}
 
+	@SuppressWarnings("deprecation")
 	private static class PeriodicTestExtractor implements AssignerWithPeriodicWatermarks<Long> {
 
 		private volatile long maxTimestamp = Long.MIN_VALUE;
@@ -583,6 +584,7 @@ public class AbstractFetcherTest {
 		}
 	}
 
+	@SuppressWarnings("deprecation")
 	private static class PunctuatedTestExtractor implements AssignerWithPunctuatedWatermarks<Long> {
 
 		@Override