Remove unnecessary lambda (#1329)

> Returning a lambda from a helper method or saving it in a constant is unnecessary; prefer to implement the functional interface method directly and use a method reference instead.

https://errorprone.info/bugpattern/UnnecessaryLambda

amazon-kinesis-client/src/main/java/software/amazon/kinesis/leases/HierarchicalShardSyncer.java

@@ -25,7 +25,6 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
@@ -99,11 +98,11 @@ public HierarchicalShardSyncer(final boolean isMultiStreamMode, final String str
  this.deletedStreamListProvider = deletedStreamListProvider;
  }
 
- private static final BiFunction<Lease, MultiStreamArgs, String> SHARD_ID_FROM_LEASE_DEDUCER =
-  (lease, multiStreamArgs) ->
- multiStreamArgs.isMultiStreamMode() ?
-  ((MultiStreamLease) lease).shardId() :
-  lease.leaseKey();
+ private static String getShardIdFromLease(Lease lease, MultiStreamArgs multiStreamArgs) {
+ return multiStreamArgs.isMultiStreamMode()
+ ? ((MultiStreamLease) lease).shardId()
+ : lease.leaseKey();
+ }
 
  /**
  * Check and create leases for any new shards (e.g. following a reshard operation). Sync leases with Kinesis shards
@@ -739,8 +738,8 @@ private static class StartingSequenceNumberAndShardIdBasedComparator implements
  @Override
  public int compare(final Lease lease1, final Lease lease2) {
  int result = 0;
- final String shardId1 = SHARD_ID_FROM_LEASE_DEDUCER.apply(lease1, multiStreamArgs);
- final String shardId2 = SHARD_ID_FROM_LEASE_DEDUCER.apply(lease2, multiStreamArgs);
+ final String shardId1 = getShardIdFromLease(lease1, multiStreamArgs);
+ final String shardId2 = getShardIdFromLease(lease2, multiStreamArgs);
  final Shard shard1 = shardIdToShardMap.get(shardId1);
  final Shard shard2 = shardIdToShardMap.get(shardId2);
 
@@ -813,7 +812,7 @@ public List<Lease> determineNewLeasesToCreate(List<Shard> shards, List<Lease> cu
  final Map<String, Shard> shardIdToShardMapOfAllKinesisShards = constructShardIdToShardMap(shards);
 
  currentLeases.stream().peek(lease -> log.debug("{} : Existing lease: {}", streamIdentifier, lease))
- .map(lease -> SHARD_ID_FROM_LEASE_DEDUCER.apply(lease, multiStreamArgs))
+ .map(lease -> getShardIdFromLease(lease, multiStreamArgs))
  .collect(Collectors.toSet());
 
  final List<Lease> newLeasesToCreate = getLeasesToCreateForOpenAndClosedShards(initialPosition, shards, multiStreamArgs, streamIdentifier);
@@ -919,7 +918,7 @@ public synchronized List<Lease> determineNewLeasesToCreate(final List<Shard> sha
  .map(streamId -> streamId.serialize()).orElse("");
  final Set<String> shardIdsOfCurrentLeases = currentLeases.stream()
  .peek(lease -> log.debug("{} : Existing lease: {}", streamIdentifier, lease))
- .map(lease -> SHARD_ID_FROM_LEASE_DEDUCER.apply(lease, multiStreamArgs))
+ .map(lease -> getShardIdFromLease(lease, multiStreamArgs))
  .collect(Collectors.toSet());
 
  final List<Shard> openShards = getOpenShards(shards, streamIdentifier);