Address comments

Signed-off-by: John Mazanec <[email protected]>

src/main/java/org/opensearch/knn/index/memory/NativeMemoryCacheManagerDto.java

@@ -6,13 +6,13 @@
 package org.opensearch.knn.index.memory;
 
 import lombok.Builder;
-import lombok.Getter;
+import lombok.Value;
 
-@Getter
+@Value
 @Builder
 public class NativeMemoryCacheManagerDto {
-    private final boolean isWeightLimited;
-    private final long maxWeight;
-    private final boolean isExpirationLimited;
-    private final long expiryTimeInMin;
+    boolean isWeightLimited;
+    long maxWeight;
+    boolean isExpirationLimited;
+    long expiryTimeInMin;
 }

src/test/java/org/opensearch/knn/KNNTestCase.java

@@ -5,6 +5,8 @@
 
 package org.opensearch.knn;
 
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
 import org.opensearch.cluster.service.ClusterService;
 import org.opensearch.common.settings.ClusterSettings;
 import org.opensearch.common.settings.Setting;
@@ -22,26 +24,36 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 /**
  * Base class for integration tests for KNN plugin. Contains several methods for testing KNN ES functionality.
  */
 public class KNNTestCase extends OpenSearchTestCase {
+
+    @Mock
+    protected ClusterService clusterService;
+    private AutoCloseable openMocks;
+
+    @Override
+    public void setUp() throws Exception {
+        super.setUp();
+        openMocks = MockitoAnnotations.openMocks(this);
+    }
+
     @Override
     public void tearDown() throws Exception {
         super.tearDown();
         resetState();
+        openMocks.close();
     }
 
-    public static void resetState() {
+    public void resetState() {
         // Reset all of the counters
         for (KNNCounter knnCounter : KNNCounter.values()) {
             knnCounter.set(0L);
         }
 
-        ClusterService clusterService = mock(ClusterService.class);
         Set<Setting<?>> defaultClusterSettings = new HashSet<>(ClusterSettings.BUILT_IN_CLUSTER_SETTINGS);
         defaultClusterSettings.addAll(
             KNNSettings.state()