FME-15373-impressions: git mv pure-leaf impression files, DTOs, filters, and clean strategy files to impressions module

- Move impression DTOs (KeyImpression, TestImpressions, ImpressionCount, DecoratedImpression, UniqueKeys)
- Move core impression files (Impression, ImpressionCounter, ImpressionHasher, ImpressionObserver,
  ImpressionUtils, ImpressionsResult, ImpressionsSender, ImpressionsStorage*, InMemoryImpressionsStorage,
  ImpressionsManager, ImpressionListener, UniqueKeysTracker)
- Move filters/ package wholesale (BloomFilterImp, Filter, FilterAdapter, FilterAdapterImpl)
- Move clean strategy files (ProcessImpressionDebug, ProcessImpressionNone, ProcessImpressionStrategy)
- Copy MurmurHash3 into impressions module to avoid targeting-engine dependency
- Replace Preconditions.checkNotNull with Objects.requireNonNull in ImpressionCounter
- Add hamcrest-all test dep; fix ImpressionObserverTest logger reference
- impressions module builds and all moved tests pass standalone

AI-Session-Id: 52375eb8-af89-45b8-bbad-1698b6636202
AI-Tool: claude-code
AI-Model: unknown

Author: gthea

impressions/pom.xml

@@ -37,6 +37,12 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest-all</artifactId>
+      <version>1.3</version>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>

…lit/client/dtos/DecoratedImpression.java …lit/client/dtos/DecoratedImpression.javaclient/src/main/java/io/split/client/dtos/DecoratedImpression.java renamed to impressions/src/main/java/io/split/client/dtos/DecoratedImpression.java client/src/main/java/io/split/client/dtos/DecoratedImpression.java renamed to impressions/src/main/java/io/split/client/dtos/DecoratedImpression.java

@@ -5,16 +5,14 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
 public class ImpressionCounter {
 
     public static class Key {
         private final String _featureName;
         private final long _timeFrame;
 
         public Key(String featureFlagName, long timeframe) {
-            _featureName = checkNotNull(featureFlagName);
+            _featureName = Objects.requireNonNull(featureFlagName);
             _timeFrame = timeframe;
         }