Prohibit LinkedList (#6112)

* Prohibit LinkedList

* Fix tests

* Fix

* Remove unused import

api/src/main/java/org/apache/druid/guice/LifecycleScope.java

@@ -19,13 +19,13 @@
 
 package org.apache.druid.guice;
 
-import com.google.common.collect.Lists;
 import com.google.inject.Key;
 import com.google.inject.Provider;
 import com.google.inject.Scope;
 import org.apache.druid.java.util.common.lifecycle.Lifecycle;
 import org.apache.druid.java.util.common.logger.Logger;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -37,7 +37,7 @@ public class LifecycleScope implements Scope
   private final Lifecycle.Stage stage;
 
   private Lifecycle lifecycle;
-  private final List<Object> instances = Lists.newLinkedList();
+  private final List<Object> instances = new ArrayList<>();
 
   public LifecycleScope(Lifecycle.Stage stage)
   {

codestyle/druid-forbidden-apis.txt

@@ -5,3 +5,7 @@ com.google.common.collect.Iterators#emptyIterator() @ Use java.util.Collections#
 com.google.common.base.Charsets @ Use java.nio.charset.StandardCharsets instead
 java.io.File#toURL() @ Use java.io.File#toURI() and java.net.URI#toURL() instead
 org.apache.commons.io.FileUtils#getTempDirectory() @ Use org.junit.rules.TemporaryFolder for tests instead
+
+java.util.LinkedList @ Use ArrayList or ArrayDeque instead
+com.google.common.collect.Lists#newLinkedList() @ Use ArrayList or ArrayDeque instead
+com.google.common.collect.Lists#newLinkedList(java.lang.Iterable) @ Use ArrayList or ArrayDeque instead

extensions-core/histogram/src/test/java/org/apache/druid/query/aggregation/histogram/ApproximateHistogramTest.java

@@ -20,12 +20,12 @@
 package org.apache.druid.query.aggregation.histogram;
 
 import com.google.common.collect.Iterators;
-import com.google.common.collect.Lists;
 import org.apache.druid.java.util.common.StringUtils;
 import org.junit.Assert;
 import org.junit.Test;
 
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Random;
@@ -239,7 +239,7 @@ public class ApproximateHistogramTest
       randNums[i] = (float) rand.nextGaussian();
     }
 
-    List<ApproximateHistogram> randHist = Lists.newLinkedList();
+    List<ApproximateHistogram> randHist = new ArrayList<>();
     Iterator<ApproximateHistogram> it = Iterators.cycle(randHist);
 
     for (int k = 0; k < numRand; ++k) {

extensions-core/kafka-indexing-service/src/main/java/org/apache/druid/indexing/kafka/IncrementalPublishingKafkaIndexTaskRunner.java

@@ -99,11 +99,11 @@ import javax.ws.rs.core.Response;
 import java.io.File;
 import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -181,8 +181,8 @@ public class IncrementalPublishingKafkaIndexTaskRunner implements KafkaIndexTask
   private final RowIngestionMeters rowIngestionMeters;
 
   private final Set<String> publishingSequences = Sets.newConcurrentHashSet();
-  private final List<ListenableFuture<SegmentsAndMetadata>> publishWaitList = new LinkedList<>();
+  private final List<ListenableFuture<SegmentsAndMetadata>> publishWaitList = new ArrayList<>();
-  private final List<ListenableFuture<SegmentsAndMetadata>> handOffWaitList = new LinkedList<>();
+  private final List<ListenableFuture<SegmentsAndMetadata>> handOffWaitList = new ArrayList<>();
 
   private volatile DateTime startTime;
   private volatile Status status = Status.NOT_STARTED; // this is only ever set by the task runner thread (runThread)

hll/src/test/java/org/apache/druid/hll/HyperLogLogCollectorBenchmark.java

@@ -23,7 +23,6 @@ import com.google.caliper.Param;
 import com.google.caliper.Runner;
 import com.google.caliper.SimpleBenchmark;
 import com.google.common.base.Preconditions;
-import com.google.common.collect.Lists;
 import com.google.common.hash.HashFunction;
 import com.google.common.hash.Hashing;
 import sun.misc.Unsafe;
@@ -31,6 +30,7 @@ import sun.misc.Unsafe;
 import java.lang.reflect.Field;
 import java.nio.Buffer;
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
@@ -41,7 +41,7 @@ public class HyperLogLogCollectorBenchmark extends SimpleBenchmark
 {
   private final HashFunction fn = Hashing.murmur3_128();
 
-  private final List<HyperLogLogCollector> collectors = Lists.newLinkedList();
+  private final List<HyperLogLogCollector> collectors = new ArrayList<>();
 
   @Param({"true"}) boolean targetIsDirect;
   @Param({"default", "random", "0"}) String alignment;

indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java

@@ -29,6 +29,7 @@ import com.google.common.collect.Lists;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
+import org.apache.commons.io.FileUtils;
 import org.apache.druid.client.cache.CacheConfig;
 import org.apache.druid.client.cache.CachePopulatorStats;
 import org.apache.druid.client.cache.MapCache;
@@ -49,12 +50,12 @@ import org.apache.druid.discovery.DruidNodeAnnouncer;
 import org.apache.druid.discovery.LookupNodeService;
 import org.apache.druid.indexer.IngestionState;
 import org.apache.druid.indexer.TaskState;
+import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexing.common.Counters;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReportData;
 import org.apache.druid.indexing.common.SegmentLoaderFactory;
 import org.apache.druid.indexing.common.TaskReport;
 import org.apache.druid.indexing.common.TaskReportFileWriter;
-import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.TaskToolboxFactory;
 import org.apache.druid.indexing.common.TestUtils;
@@ -133,7 +134,6 @@ import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.partition.LinearShardSpec;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
 import org.apache.druid.utils.Runnables;
-import org.apache.commons.io.FileUtils;
 import org.easymock.EasyMock;
 import org.joda.time.DateTime;
 import org.joda.time.Period;
@@ -149,10 +149,11 @@ import javax.annotation.Nullable;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.LinkedList;
+import java.util.Deque;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -178,7 +179,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
   private static class TestFirehose implements Firehose
   {
     private final InputRowParser<Map<String, Object>> parser;
-    private final List<Map<String, Object>> queue = new LinkedList<>();
+    private final Deque<Optional<Map<String, Object>>> queue = new ArrayDeque<>();
     private boolean closed = false;
 
     public TestFirehose(final InputRowParser<Map<String, Object>> parser)
@@ -189,7 +190,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     public void addRows(List<Map<String, Object>> rows)
     {
       synchronized (this) {
-        queue.addAll(rows);
+        rows.stream().map(Optional::ofNullable).forEach(queue::add);
         notifyAll();
       }
     }
@@ -215,7 +216,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     public InputRow nextRow()
     {
       synchronized (this) {
-        final InputRow row = parser.parseBatch(queue.remove(0)).get(0);
+        final InputRow row = parser.parseBatch(queue.removeFirst().orElse(null)).get(0);
         if (row != null && row.getRaw(FAIL_DIM) != null) {
           throw new ParseException(FAIL_DIM);
         }

indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java

@@ -46,9 +46,9 @@ import org.apache.druid.discovery.DataNodeService;
 import org.apache.druid.discovery.DruidNodeAnnouncer;
 import org.apache.druid.discovery.LookupNodeService;
 import org.apache.druid.indexer.TaskState;
+import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexing.common.Counters;
 import org.apache.druid.indexing.common.SegmentLoaderFactory;
-import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.TaskToolboxFactory;
 import org.apache.druid.indexing.common.TestUtils;
@@ -138,10 +138,12 @@ import org.junit.rules.TemporaryFolder;
 import javax.annotation.Nullable;
 import java.io.File;
 import java.nio.file.Files;
+import java.util.ArrayDeque;
 import java.util.Arrays;
-import java.util.LinkedList;
+import java.util.Deque;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
@@ -161,7 +163,7 @@ public class RealtimeIndexTaskTest
   private static class TestFirehose implements Firehose
   {
     private final InputRowParser<Map<String, Object>> parser;
-    private final List<Map<String, Object>> queue = new LinkedList<>();
+    private final Deque<Optional<Map<String, Object>>> queue = new ArrayDeque<>();
     private boolean closed = false;
 
     public TestFirehose(final InputRowParser<Map<String, Object>> parser)
@@ -172,7 +174,7 @@ public class RealtimeIndexTaskTest
     public void addRows(List<Map<String, Object>> rows)
     {
       synchronized (this) {
-        queue.addAll(rows);
+        rows.stream().map(Optional::ofNullable).forEach(queue::add);
         notifyAll();
       }
     }
@@ -198,7 +200,7 @@ public class RealtimeIndexTaskTest
     public InputRow nextRow()
     {
       synchronized (this) {
-        final InputRow row = parser.parseBatch(queue.remove(0)).get(0);
+        final InputRow row = parser.parseBatch(queue.removeFirst().orElse(null)).get(0);
         if (row != null && row.getRaw(FAIL_DIM) != null) {
           throw new ParseException(FAIL_DIM);
         }

indexing-service/src/test/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactoryTest.java

@@ -110,7 +110,6 @@ import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -324,7 +323,7 @@ public class IngestSegmentFirehoseFactoryTest
         null,
         new NoopTestTaskFileWriter()
     );
-    Collection<Object[]> values = new LinkedList<>();
+    Collection<Object[]> values = new ArrayList<>();
     for (InputRowParser parser : Arrays.<InputRowParser>asList(
         ROW_PARSER,
         new MapInputRowParser(

java-util/src/main/java/org/apache/druid/java/util/http/client/io/AppendableByteArrayInputStream.java

@@ -23,7 +23,8 @@ import org.apache.druid.java.util.common.logger.Logger;
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.LinkedList;
+import java.util.ArrayDeque;
+import java.util.Deque;
 
 /**
  */
@@ -31,7 +32,7 @@ public class AppendableByteArrayInputStream extends InputStream
 {
   private static final Logger log = new Logger(AppendableByteArrayInputStream.class);
 
-  private final LinkedList<byte[]> bytes = new LinkedList<byte[]>();
+  private final Deque<byte[]> bytes = new ArrayDeque<>();
   private final SingleByteReaderDoer singleByteReaderDoer = new SingleByteReaderDoer();
 
   private volatile boolean done = false;

processing/src/main/java/org/apache/druid/query/aggregation/AggregatorUtil.java

@@ -37,8 +37,9 @@ import org.apache.druid.segment.FloatColumnSelector;
 import org.apache.druid.segment.LongColumnSelector;
 import org.apache.druid.segment.virtual.ExpressionSelectors;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
 
@@ -113,18 +114,20 @@ public class AggregatorUtil
    */
   public static List<PostAggregator> pruneDependentPostAgg(List<PostAggregator> postAggregatorList, String postAggName)
   {
-    LinkedList<PostAggregator> rv = Lists.newLinkedList();
+    ArrayList<PostAggregator> rv = new ArrayList<>();
     Set<String> deps = new HashSet<>();
     deps.add(postAggName);
-    // Iterate backwards to find the last calculated aggregate and add dependent aggregator as we find dependencies in reverse order
+    // Iterate backwards to find the last calculated aggregate and add dependent aggregator as we find dependencies
+    // in reverse order
     for (PostAggregator agg : Lists.reverse(postAggregatorList)) {
       if (deps.contains(agg.getName())) {
-        rv.addFirst(agg); // add to the beginning of List
+        rv.add(agg); // add to the beginning of List
         deps.remove(agg.getName());
         deps.addAll(agg.getDependentFields());
       }
     }
 
+    Collections.reverse(rv);
     return rv;
   }
 
@@ -135,10 +138,7 @@ public class AggregatorUtil
   )
   {
 
-    List<PostAggregator> condensedPostAggs = AggregatorUtil.pruneDependentPostAgg(
+    List<PostAggregator> condensedPostAggs = AggregatorUtil.pruneDependentPostAgg(postAggList, metric);
-        postAggList,
-        metric
-    );
     // calculate dependent aggregators for these postAgg
     Set<String> dependencySet = new HashSet<>();
     dependencySet.add(metric);
@@ -152,7 +152,7 @@ public class AggregatorUtil
         condensedAggs.add(aggregatorSpec);
       }
     }
-    return new Pair(condensedAggs, condensedPostAggs);
+    return new Pair<>(condensedAggs, condensedPostAggs);
   }
 
   public static BaseFloatColumnValueSelector makeColumnValueSelectorWithFloatDefault(

processing/src/main/java/org/apache/druid/query/topn/AggregateTopNMetricFirstAlgorithm.java

@@ -75,11 +75,8 @@ public class AggregateTopNMetricFirstAlgorithm implements TopNAlgorithm<int[], T
   )
   {
     final String metric = query.getTopNMetricSpec().getMetricName(query.getDimensionSpec());
-    Pair<List<AggregatorFactory>, List<PostAggregator>> condensedAggPostAggPair = AggregatorUtil.condensedAggregators(
+    Pair<List<AggregatorFactory>, List<PostAggregator>> condensedAggPostAggPair =
-        query.getAggregatorSpecs(),
+        AggregatorUtil.condensedAggregators(query.getAggregatorSpecs(), query.getPostAggregatorSpecs(), metric);
-        query.getPostAggregatorSpecs(),
-        metric
-    );
 
     if (condensedAggPostAggPair.lhs.isEmpty() && condensedAggPostAggPair.rhs.isEmpty()) {
       throw new ISE("WTF! Can't find the metric to do topN over?");

processing/src/main/java/org/apache/druid/query/topn/TopNQueryBuilder.java

@@ -37,7 +37,9 @@ import org.apache.druid.segment.VirtualColumn;
 import org.apache.druid.segment.VirtualColumns;
 import org.joda.time.Interval;
 
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -247,13 +249,13 @@ public class TopNQueryBuilder
   @SuppressWarnings("unchecked")
   public TopNQueryBuilder aggregators(List<? extends AggregatorFactory> a)
   {
-    aggregatorSpecs = (List<AggregatorFactory>) a;
+    aggregatorSpecs = new ArrayList<>(a); // defensive copy
     return this;
   }
 
-  public TopNQueryBuilder postAggregators(List<PostAggregator> p)
+  public TopNQueryBuilder postAggregators(Collection<PostAggregator> p)
   {
-    postAggregatorSpecs = p;
+    postAggregatorSpecs = new ArrayList<>(p); // defensive copy
     return this;
   }
 

processing/src/test/java/org/apache/druid/query/aggregation/AggregatorUtilTest.java

@@ -172,7 +172,8 @@ public class AggregatorUtilTest
     );
 
     Assert.assertEquals(
-        new Pair(Lists.newArrayList(agg1, agg2), Collections.singletonList(postAgg2)), AggregatorUtil.condensedAggregators(
+        new Pair<>(Lists.newArrayList(agg1, agg2), Collections.singletonList(postAgg2)),
+        AggregatorUtil.condensedAggregators(
             Lists.newArrayList(agg1, agg2),
             Lists.newArrayList(postAgg1, postAgg2),
             "postAgg"

processing/src/test/java/org/apache/druid/query/scan/ScanQueryRunnerTest.java

@@ -54,6 +54,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
@@ -754,11 +755,11 @@ public class ScanQueryRunnerTest
       @Override
       public ScanResultValue apply(ScanResultValue input)
       {
-        List mapEvents = Lists.newLinkedList();
+        List<Map<String, Object>> mapEvents = new ArrayList<>();
-        List events = ((List) input.getEvents());
+        List<?> events = ((List<?>) input.getEvents());
         for (Object event : events) {
-          Iterator compactedEventIter = ((List) event).iterator();
+          Iterator<?> compactedEventIter = ((List<?>) event).iterator();
-          Map mapEvent = new LinkedHashMap();
+          Map<String, Object> mapEvent = new LinkedHashMap<>();
           for (String column : input.getColumns()) {
             mapEvent.put(column, compactedEventIter.next());
           }

processing/src/test/java/org/apache/druid/query/search/SearchQueryRunnerTest.java

@@ -21,7 +21,6 @@ package org.apache.druid.query.search;
 
 import com.google.common.base.Suppliers;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Lists;
 import org.apache.druid.common.config.NullHandling;
 import org.apache.druid.data.input.MapBasedInputRow;
 import org.apache.druid.java.util.common.DateTimes;
@@ -64,6 +63,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -135,7 +135,7 @@ public class SearchQueryRunnerTest
                                     .query("a")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "mezzanine", 279));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "travel", 93));
@@ -178,7 +178,7 @@ public class SearchQueryRunnerTest
         }
     );
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 91));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "mezzanine", 273));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "travel", 91));
@@ -207,7 +207,7 @@ public class SearchQueryRunnerTest
                                     .query("e")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementDimension, "preferred", 1209));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementishDimension, "e", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementishDimension, "preferred", 1209));
@@ -232,7 +232,7 @@ public class SearchQueryRunnerTest
                                     .query("e")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementishDimension, "e", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementDimension, "preferred", 1209));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementishDimension, "preferred", 1209));
@@ -250,7 +250,7 @@ public class SearchQueryRunnerTest
                                     .query(new FragmentSearchQuerySpec(Arrays.asList("auto", "ve")))
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
 
     checkSearchQuery(searchQuery, expectedHits);
@@ -259,7 +259,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithDimensionQuality()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "mezzanine", 279));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "travel", 93));
@@ -281,7 +281,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithDimensionProvider()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "total_market", 186));
 
     checkSearchQuery(
@@ -299,7 +299,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithDimensionsQualityAndProvider()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "mezzanine", 279));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "travel", 93));
@@ -327,7 +327,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithDimensionsPlacementAndProvider()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "total_market", 186));
 
     checkSearchQuery(
@@ -352,7 +352,7 @@ public class SearchQueryRunnerTest
   public void testSearchWithExtractionFilter1()
   {
     final String automotiveSnowman = "automotive☃";
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, automotiveSnowman, 93));
 
     final LookupExtractionFn lookupExtractionFn = new LookupExtractionFn(
@@ -391,7 +391,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithSingleFilter1()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "mezzanine", 93));
 
     checkSearchQuery(
@@ -415,7 +415,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithSingleFilter2()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "total_market", 186));
 
     checkSearchQuery(
@@ -434,7 +434,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchMultiAndFilter()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
 
     DimFilter filter = new AndDimFilter(
@@ -458,7 +458,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithMultiOrFilter()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
 
     DimFilter filter = new OrDimFilter(
@@ -482,7 +482,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithEmptyResults()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
 
     checkSearchQuery(
         Druids.newSearchQueryBuilder()
@@ -498,7 +498,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchWithFilterEmptyResults()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
 
     DimFilter filter = new AndDimFilter(
         new SelectorDimFilter(QueryRunnerTestHelper.marketDimension, "total_market", null),
@@ -521,7 +521,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchNonExistingDimension()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
 
     checkSearchQuery(
         Druids.newSearchQueryBuilder()
@@ -538,7 +538,7 @@ public class SearchQueryRunnerTest
   @Test
   public void testSearchAll()
   {
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "spot", 837));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "total_market", 186));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.marketDimension, "upfront", 186));
@@ -575,7 +575,7 @@ public class SearchQueryRunnerTest
                                     .sortSpec(new SearchSortSpec(StringComparators.NUMERIC))
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.placementishDimension, "a", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "automotive", 93));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.qualityDimension, "entertainment", 93));
@@ -609,7 +609,7 @@ public class SearchQueryRunnerTest
                                     ))
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit("__time2", "Friday", 169));
 
     checkSearchQuery(searchQuery, expectedHits);
@@ -631,7 +631,7 @@ public class SearchQueryRunnerTest
                                     .query("1297123200000")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(Column.TIME_COLUMN_NAME, "1297123200000", 13));
     checkSearchQuery(searchQuery, expectedHits);
   }
@@ -655,7 +655,7 @@ public class SearchQueryRunnerTest
                                     .query("1297123200000")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(Column.TIME_COLUMN_NAME, "super-1297123200000", 13));
     checkSearchQuery(searchQuery, expectedHits);
   }
@@ -676,7 +676,7 @@ public class SearchQueryRunnerTest
                                     .query("100.7")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.indexMetric, "100.706057", 1));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.indexMetric, "100.775597", 1));
     checkSearchQuery(searchQuery, expectedHits);
@@ -701,7 +701,7 @@ public class SearchQueryRunnerTest
                                     .query("100.7")
                                     .build();
 
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.indexMetric, "super-100.706057", 1));
     expectedHits.add(new SearchHit(QueryRunnerTestHelper.indexMetric, "super-100.775597", 1));
     checkSearchQuery(searchQuery, expectedHits);
@@ -751,7 +751,7 @@ public class SearchQueryRunnerTest
         QueryRunnerTestHelper.NOOP_QUERYWATCHER
     );
     QueryRunner runner = factory.createRunner(new QueryableIndexSegment("asdf", TestIndex.persistRealtimeAndLoadMMapped(index)));
-    List<SearchHit> expectedHits = Lists.newLinkedList();
+    List<SearchHit> expectedHits = new ArrayList<>();
     expectedHits.add(new SearchHit("table", "table", 1));
     expectedHits.add(new SearchHit("table", NullHandling.defaultStringValue(), 1));
     checkSearchQuery(searchQuery, runner, expectedHits);
@@ -769,7 +769,7 @@ public class SearchQueryRunnerTest
                                     .intervals(QueryRunnerTestHelper.fullOnInterval)
                                     .build();
 
-    List<SearchHit> noHit = Lists.newLinkedList();
+    List<SearchHit> noHit = new ArrayList<>();
     checkSearchQuery(searchQuery, noHit);
   }
 
@@ -782,7 +782,7 @@ public class SearchQueryRunnerTest
   private void checkSearchQuery(Query searchQuery, QueryRunner runner, List<SearchHit> expectedResults)
   {
     Iterable<Result<SearchResultValue>> results = runner.run(QueryPlus.wrap(searchQuery), ImmutableMap.of()).toList();
-    List<SearchHit> copy = Lists.newLinkedList(expectedResults);
+    List<SearchHit> copy = new ArrayList<>(expectedResults);
     for (Result<SearchResultValue> result : results) {
       Assert.assertEquals(DateTimes.of("2011-01-12T00:00:00.000Z"), result.getTimestamp());
       Assert.assertTrue(result.getValue() instanceof Iterable);

processing/src/test/java/org/apache/druid/segment/data/BenchmarkIndexibleWrites.java

@@ -36,9 +36,9 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.ConcurrentHashMap;
@@ -196,7 +196,7 @@ public class BenchmarkIndexibleWrites extends AbstractBenchmark
         )
     );
     final AtomicInteger index = new AtomicInteger(0);
-    List<ListenableFuture<?>> futures = new LinkedList<>();
+    List<ListenableFuture<?>> futures = new ArrayList<>();
 
     final Integer loops = totalIndexSize / concurrentThreads;
 
@@ -249,7 +249,7 @@ public class BenchmarkIndexibleWrites extends AbstractBenchmark
     );
     final AtomicInteger index = new AtomicInteger(0);
     final AtomicInteger queryableIndex = new AtomicInteger(0);
-    List<ListenableFuture<?>> futures = new LinkedList<>();
+    List<ListenableFuture<?>> futures = new ArrayList<>();
 
     final Integer loops = totalIndexSize / concurrentThreads;
 

processing/src/test/java/org/apache/druid/segment/incremental/OnheapIncrementalIndexBenchmark.java

@@ -68,7 +68,6 @@ import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -347,8 +346,8 @@ public class OnheapIncrementalIndexBenchmark extends AbstractBenchmark
     );
     final long timestamp = System.currentTimeMillis();
     final Interval queryInterval = Intervals.of("1900-01-01T00:00:00Z/2900-01-01T00:00:00Z");
-    final List<ListenableFuture<?>> indexFutures = new LinkedList<>();
+    final List<ListenableFuture<?>> indexFutures = new ArrayList<>();
-    final List<ListenableFuture<?>> queryFutures = new LinkedList<>();
+    final List<ListenableFuture<?>> queryFutures = new ArrayList<>();
     final Segment incrementalIndexSegment = new IncrementalIndexSegment(incrementalIndex, null);
     final QueryRunnerFactory factory = new TimeseriesQueryRunnerFactory(
         new TimeseriesQueryQueryToolChest(QueryRunnerTestHelper.NoopIntervalChunkingQueryRunnerDecorator()),

server/src/main/java/org/apache/druid/client/CachingQueryRunner.java

@@ -38,10 +38,10 @@ import org.apache.druid.query.QueryToolChest;
 import org.apache.druid.query.SegmentDescriptor;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.Map;
 
 public class CachingQueryRunner<T> implements QueryRunner<T>
@@ -134,7 +134,7 @@ public class CachingQueryRunner<T> implements QueryRunner<T>
       }
     }
 
-    final Collection<ListenableFuture<?>> cacheFutures = Collections.synchronizedList(new LinkedList<>());
+    final Collection<ListenableFuture<?>> cacheFutures = Collections.synchronizedList(new ArrayList<>());
     if (populateCache) {
       final Function cacheFn = strategy.prepareForSegmentLevelCache();
       return cachePopulator.wrap(base.run(queryPlus, responseContext), value -> cacheFn.apply(value), cache, key);

server/src/main/java/org/apache/druid/client/cache/BackgroundCachePopulator.java

@@ -32,7 +32,7 @@ import org.apache.druid.java.util.common.guava.Sequences;
 import org.apache.druid.java.util.common.logger.Logger;
 
 import java.io.ByteArrayOutputStream;
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.function.Function;
@@ -67,7 +67,7 @@ public class BackgroundCachePopulator implements CachePopulator
       final Cache.NamedKey cacheKey
   )
   {
-    final List<ListenableFuture<CacheType>> cacheFutures = new LinkedList<>();
+    final List<ListenableFuture<CacheType>> cacheFutures = new ArrayList<>();
 
     final Sequence<T> wrappedSequence = Sequences.map(
         sequence,

server/src/main/java/org/apache/druid/client/cache/MapCache.java

@@ -19,12 +19,12 @@
 
 package org.apache.druid.client.cache;
 
-import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.primitives.Ints;
 import org.apache.druid.java.util.emitter.service.ServiceEmitter;
 
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
@@ -127,7 +127,7 @@ public class MapCache implements Cache
     }
     synchronized (clearLock) {
       Iterator<ByteBuffer> iter = baseMap.keySet().iterator();
-      List<ByteBuffer> toRemove = Lists.newLinkedList();
+      List<ByteBuffer> toRemove = new ArrayList<>();
       while (iter.hasNext()) {
         ByteBuffer next = iter.next();
 

server/src/main/java/org/apache/druid/metadata/SQLMetadataStorageActionHandler.java

@@ -24,7 +24,6 @@ import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Optional;
-import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import org.apache.druid.indexer.TaskInfo;
 import org.apache.druid.java.util.common.DateTimes;
@@ -47,6 +46,7 @@ import javax.annotation.Nullable;
 import java.io.IOException;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -488,20 +488,10 @@ public abstract class SQLMetadataStorageActionHandler<EntryType, StatusType, Log
                 .bind("entryId", entryId)
                 .map(ByteArrayMapper.FIRST)
                 .fold(
-                    Lists.newLinkedList(),
+                    new ArrayList<>(),
-                    new Folder3<List<LogType>, byte[]>()
+                    (List<LogType> list, byte[] bytes, FoldController control, StatementContext ctx) -> {
-                    {
-                      @Override
-                      public List<LogType> fold(
-                          List<LogType> list, byte[] bytes, FoldController control, StatementContext ctx
-                      ) throws SQLException
-                      {
                       try {
-                          list.add(
+                        list.add(jsonMapper.readValue(bytes, logType));
-                              jsonMapper.readValue(
-                                  bytes, logType
-                              )
-                          );
                         return list;
                       }
                       catch (IOException e) {
@@ -512,7 +502,6 @@ public abstract class SQLMetadataStorageActionHandler<EntryType, StatusType, Log
                         throw new SQLException(e);
                       }
                     }
-                    }
                 );
           }
         }

server/src/main/java/org/apache/druid/server/coordination/SegmentLoadDropHandler.java

@@ -624,7 +624,7 @@ public class SegmentLoadDropHandler implements DataSegmentChangeHandler
               synchronized (lock) {
                 try {
                   if (!(finished && queue.isEmpty())) {
-                    final List<DataSegment> segments = Lists.newLinkedList();
+                    final List<DataSegment> segments = new ArrayList<>();
                     queue.drainTo(segments);
                     try {
                       announcer.announceSegments(segments);
@@ -656,7 +656,7 @@ public class SegmentLoadDropHandler implements DataSegmentChangeHandler
         finished = true;
         // announce any remaining segments
         try {
-          final List<DataSegment> segments = Lists.newLinkedList();
+          final List<DataSegment> segments = new ArrayList<>();
           queue.drainTo(segments);
           announcer.announceSegments(segments);
         }

server/src/test/java/org/apache/druid/client/cache/ByteCountingLRUMapTest.java

@@ -19,12 +19,12 @@
 
 package org.apache.druid.client.cache;
 
-import com.google.common.collect.Lists;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.nio.ByteBuffer;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
@@ -70,7 +70,7 @@ public class ByteCountingLRUMapTest
     Assert.assertEquals(oneByte, ByteBuffer.wrap(map.get(twoByte)));
 
     Iterator<ByteBuffer> it = map.keySet().iterator();
-    List<ByteBuffer> toRemove = Lists.newLinkedList();
+    List<ByteBuffer> toRemove = new ArrayList<>();
     while (it.hasNext()) {
       ByteBuffer buf = it.next();
       if (buf.remaining() == 10) {

server/src/test/java/org/apache/druid/metadata/SQLMetadataConnectorTest.java

@@ -26,7 +26,8 @@ import org.junit.Test;
 import org.skife.jdbi.v2.Handle;
 import org.skife.jdbi.v2.tweak.HandleCallback;
 
-import java.util.LinkedList;
+import java.util.ArrayList;
+import java.util.List;
 
 
 public class SQLMetadataConnectorTest
@@ -47,7 +48,7 @@ public class SQLMetadataConnectorTest
   @Test
   public void testCreateTables()
   {
-    final LinkedList<String> tables = new LinkedList<String>();
+    final List<String> tables = new ArrayList<>();
     final String entryType = tablesConfig.getTaskEntryType();
     tables.add(tablesConfig.getConfigTable());
     tables.add(tablesConfig.getSegmentsTable());

server/src/test/java/org/apache/druid/server/coordination/SegmentLoadDropHandlerTest.java

@@ -23,7 +23,6 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Lists;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import org.apache.druid.java.util.common.Intervals;
@@ -274,7 +273,7 @@ public class SegmentLoadDropHandlerTest
   @Test
   public void testLoadCache() throws Exception
   {
-    List<DataSegment> segments = Lists.newLinkedList();
+    List<DataSegment> segments = new ArrayList<>();
     for (int i = 0; i < COUNT; ++i) {
       segments.add(makeSegment("test" + i, "1", Intervals.of("P1d/2011-04-01")));
       segments.add(makeSegment("test" + i, "1", Intervals.of("P1d/2011-04-02")));
@@ -406,7 +405,7 @@ public class SegmentLoadDropHandlerTest
         announcer, EasyMock.createNiceMock(DataSegmentServerAnnouncer.class), segmentManager
     );
 
-    List<DataSegment> segments = Lists.newLinkedList();
+    List<DataSegment> segments = new ArrayList<>();
     for (int i = 0; i < COUNT; ++i) {
       segments.add(makeSegment("test" + i, "1", Intervals.of("P1d/2011-04-01")));
       segments.add(makeSegment("test" + i, "1", Intervals.of("P1d/2011-04-02")));