diff --git a/build.gradle b/build.gradle
index cd3673394..2e6218add 100644
--- a/build.gradle
+++ b/build.gradle
@@ -83,6 +83,7 @@ dependencies {
     testCompile group: 'ch.qos.logback', name: 'logback-classic', version: '1.2.3'
     testCompile group: 'io.grpc', name: 'grpc-testing', version: '1.54.2'
     testImplementation 'io.opentracing:opentracing-mock:0.33.0'
+    testImplementation group: 'org.mockito', name: 'mockito-core', version: '4.5.1'
 }
 
 license {
diff --git a/src/test/java/com/uber/cadence/activity/LocalActivityContextPropagationTest.java b/src/test/java/com/uber/cadence/activity/LocalActivityContextPropagationTest.java
index 2e1b4581f..4acb622d2 100644
--- a/src/test/java/com/uber/cadence/activity/LocalActivityContextPropagationTest.java
+++ b/src/test/java/com/uber/cadence/activity/LocalActivityContextPropagationTest.java
@@ -39,10 +39,7 @@
 import java.util.Map;
 import java.util.Optional;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class LocalActivityContextPropagationTest {
 
   private static final String LOCAL_ACTIVITY_CP_TASK_LIST = "LOCAL_ACTIVITY_CP_TASK_LIST";
diff --git a/src/test/java/com/uber/cadence/internal/compatibility/ProtoObjects.java b/src/test/java/com/uber/cadence/internal/compatibility/ProtoObjects.java
index 30c9100cb..3c029b8e7 100644
--- a/src/test/java/com/uber/cadence/internal/compatibility/ProtoObjects.java
+++ b/src/test/java/com/uber/cadence/internal/compatibility/ProtoObjects.java
@@ -1,3 +1,17 @@
+/**
+ * Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * <p>Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ * <p>Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file
+ * except in compliance with the License. A copy of the License is located at
+ *
+ * <p>http://aws.amazon.com/apache2.0
+ *
+ * <p>or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
 package com.uber.cadence.internal.compatibility;
 
 import com.google.common.collect.ImmutableList;
diff --git a/src/test/java/com/uber/cadence/internal/compatibility/Thrift2ProtoAdapterTest.java b/src/test/java/com/uber/cadence/internal/compatibility/Thrift2ProtoAdapterTest.java
index 62197570f..2b35eb21a 100644
--- a/src/test/java/com/uber/cadence/internal/compatibility/Thrift2ProtoAdapterTest.java
+++ b/src/test/java/com/uber/cadence/internal/compatibility/Thrift2ProtoAdapterTest.java
@@ -19,7 +19,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
-import static org.mockito.Matchers.any;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.doAnswer;
 
 import com.uber.cadence.SignalWithStartWorkflowExecutionAsyncRequest;
@@ -157,9 +157,10 @@ private void assertTracingHeaders(Header header) {
             .toString());
   }
 
+  @SuppressWarnings("CheckReturnValue")
   private <REQ, RES> ArgumentCaptor<REQ> mockRpc(
       BiConsumer<REQ, StreamObserver<RES>> method, RES value) {
-    ArgumentCaptor<REQ> captor = new ArgumentCaptor<>();
+    ArgumentCaptor<REQ> captor = ArgumentCaptor.forClass(null);
     doAnswer(
             invocation -> {
               @SuppressWarnings("unchecked")
diff --git a/src/test/java/com/uber/cadence/internal/compatibility/ThriftObjects.java b/src/test/java/com/uber/cadence/internal/compatibility/ThriftObjects.java
index d3269daa1..5c7e7308a 100644
--- a/src/test/java/com/uber/cadence/internal/compatibility/ThriftObjects.java
+++ b/src/test/java/com/uber/cadence/internal/compatibility/ThriftObjects.java
@@ -1,3 +1,17 @@
+/**
+ * Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * <p>Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ * <p>Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file
+ * except in compliance with the License. A copy of the License is located at
+ *
+ * <p>http://aws.amazon.com/apache2.0
+ *
+ * <p>or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
 package com.uber.cadence.internal.compatibility;
 
 import com.google.common.collect.ImmutableList;
diff --git a/src/test/java/com/uber/cadence/internal/compatibility/proto/DecisionMapperTest.java b/src/test/java/com/uber/cadence/internal/compatibility/proto/DecisionMapperTest.java
index 163d64858..f12ad2d53 100644
--- a/src/test/java/com/uber/cadence/internal/compatibility/proto/DecisionMapperTest.java
+++ b/src/test/java/com/uber/cadence/internal/compatibility/proto/DecisionMapperTest.java
@@ -1,3 +1,17 @@
+/**
+ * Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * <p>Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ * <p>Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file
+ * except in compliance with the License. A copy of the License is located at
+ *
+ * <p>http://aws.amazon.com/apache2.0
+ *
+ * <p>or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
 package com.uber.cadence.internal.compatibility.proto;
 
 import static com.uber.cadence.internal.compatibility.MapperTestUtil.assertMissingFields;
diff --git a/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderCacheTests.java b/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderCacheTests.java
index e790bec59..564ad78ea 100644
--- a/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderCacheTests.java
+++ b/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderCacheTests.java
@@ -19,8 +19,6 @@
 
 import static junit.framework.TestCase.assertEquals;
 import static org.junit.Assert.*;
-import static org.mockito.Matchers.anyInt;
-import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.*;
 
 import com.uber.cadence.HistoryEvent;
@@ -211,7 +209,7 @@ public void evictAnyWillInvalidateAnEntryRandomlyFromTheCache() throws Exception
     // Wait for reporter
     Thread.sleep(600);
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_TOTAL_FORCED_EVICTION), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_TOTAL_FORCED_EVICTION), eq(tags), anyLong());
   }
 
   @Test
diff --git a/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderTaskHandlerTests.java b/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderTaskHandlerTests.java
index fb9f6bbb1..186141c0a 100644
--- a/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderTaskHandlerTests.java
+++ b/src/test/java/com/uber/cadence/internal/replay/ReplayDeciderTaskHandlerTests.java
@@ -21,7 +21,7 @@
 import static junit.framework.TestCase.assertEquals;
 import static junit.framework.TestCase.assertNotNull;
 import static org.junit.Assert.assertNull;
-import static org.mockito.Matchers.any;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/shadowing/ReplayWorkflowActivityTest.java b/src/test/java/com/uber/cadence/internal/shadowing/ReplayWorkflowActivityTest.java
index 77ed1786a..4e1df82c3 100644
--- a/src/test/java/com/uber/cadence/internal/shadowing/ReplayWorkflowActivityTest.java
+++ b/src/test/java/com/uber/cadence/internal/shadowing/ReplayWorkflowActivityTest.java
@@ -23,7 +23,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Matchers.any;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/shadowing/ScanWorkflowActivityTest.java b/src/test/java/com/uber/cadence/internal/shadowing/ScanWorkflowActivityTest.java
index 187c695e4..a16bee129 100644
--- a/src/test/java/com/uber/cadence/internal/shadowing/ScanWorkflowActivityTest.java
+++ b/src/test/java/com/uber/cadence/internal/shadowing/ScanWorkflowActivityTest.java
@@ -17,8 +17,8 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/sync/DeterministicRunnerTest.java b/src/test/java/com/uber/cadence/internal/sync/DeterministicRunnerTest.java
index 36747dad0..e53c3e662 100644
--- a/src/test/java/com/uber/cadence/internal/sync/DeterministicRunnerTest.java
+++ b/src/test/java/com/uber/cadence/internal/sync/DeterministicRunnerTest.java
@@ -779,7 +779,7 @@ public void workflowThreadsWillEvictCacheWhenMaxThreadCountIsHit() throws Throwa
     // Wait for reporter
     Thread.sleep(600);
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_THREAD_FORCED_EVICTION), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_THREAD_FORCED_EVICTION), eq(tags), anyLong());
   }
 
   @Test
diff --git a/src/test/java/com/uber/cadence/internal/sync/WorkflowStubImplTest.java b/src/test/java/com/uber/cadence/internal/sync/WorkflowStubImplTest.java
index 7516634ef..4cafd2236 100644
--- a/src/test/java/com/uber/cadence/internal/sync/WorkflowStubImplTest.java
+++ b/src/test/java/com/uber/cadence/internal/sync/WorkflowStubImplTest.java
@@ -19,8 +19,8 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/testing/ActivityTestingTest.java b/src/test/java/com/uber/cadence/internal/testing/ActivityTestingTest.java
index 9603f9e4c..9275c6891 100644
--- a/src/test/java/com/uber/cadence/internal/testing/ActivityTestingTest.java
+++ b/src/test/java/com/uber/cadence/internal/testing/ActivityTestingTest.java
@@ -20,7 +20,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
-import static org.mockito.Matchers.any;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/testing/WorkflowTestingTest.java b/src/test/java/com/uber/cadence/internal/testing/WorkflowTestingTest.java
index 4cd94778a..08051a726 100644
--- a/src/test/java/com/uber/cadence/internal/testing/WorkflowTestingTest.java
+++ b/src/test/java/com/uber/cadence/internal/testing/WorkflowTestingTest.java
@@ -18,7 +18,7 @@
 package com.uber.cadence.internal.testing;
 
 import static org.junit.Assert.*;
-import static org.mockito.Matchers.anyString;
+import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
diff --git a/src/test/java/com/uber/cadence/internal/worker/PollDecisionTaskDispatcherTests.java b/src/test/java/com/uber/cadence/internal/worker/PollDecisionTaskDispatcherTests.java
index d399b40a9..cff5c3a1a 100644
--- a/src/test/java/com/uber/cadence/internal/worker/PollDecisionTaskDispatcherTests.java
+++ b/src/test/java/com/uber/cadence/internal/worker/PollDecisionTaskDispatcherTests.java
@@ -18,7 +18,6 @@
 package com.uber.cadence.internal.worker;
 
 import static junit.framework.TestCase.*;
-import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.*;
 
 import ch.qos.logback.classic.Level;
diff --git a/src/test/java/com/uber/cadence/internal/worker/WorkerShutDownHandlerTest.java b/src/test/java/com/uber/cadence/internal/worker/WorkerShutDownHandlerTest.java
index a99f27c17..7098c6f68 100644
--- a/src/test/java/com/uber/cadence/internal/worker/WorkerShutDownHandlerTest.java
+++ b/src/test/java/com/uber/cadence/internal/worker/WorkerShutDownHandlerTest.java
@@ -18,6 +18,7 @@
 package com.uber.cadence.internal.worker;
 
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import com.uber.cadence.client.WorkflowClient;
@@ -28,11 +29,8 @@
 import com.uber.m3.tally.NoopScope;
 import org.junit.Before;
 import org.junit.Test;
-import org.junit.runner.RunWith;
 import org.mockito.Mock;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class WorkerShutDownHandlerTest {
 
   @Mock private WorkflowClient mockClient;
@@ -41,6 +39,8 @@ public class WorkerShutDownHandlerTest {
 
   @Before
   public void setup() {
+    mockClient = mock(WorkflowClient.class);
+    mockService = mock(IWorkflowService.class);
     WorkflowClientOptions clientOptions =
         WorkflowClientOptions.newBuilder().setMetricsScope(new NoopScope()).build();
     when(mockClient.getOptions()).thenReturn(clientOptions);
diff --git a/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerAutoScalerTest.java b/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerAutoScalerTest.java
index dc9479e2c..f660e5c72 100644
--- a/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerAutoScalerTest.java
+++ b/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerAutoScalerTest.java
@@ -19,10 +19,7 @@
 
 import java.time.Duration;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class PollerAutoScalerTest {
 
   @Test
diff --git a/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerUsageEstimatorTest.java b/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerUsageEstimatorTest.java
index d31bcd394..2d1390c33 100644
--- a/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerUsageEstimatorTest.java
+++ b/src/test/java/com/uber/cadence/internal/worker/autoscaler/PollerUsageEstimatorTest.java
@@ -20,10 +20,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class PollerUsageEstimatorTest {
 
   @Test
diff --git a/src/test/java/com/uber/cadence/internal/worker/autoscaler/RecommenderTest.java b/src/test/java/com/uber/cadence/internal/worker/autoscaler/RecommenderTest.java
index b37a3ebdf..56384639a 100644
--- a/src/test/java/com/uber/cadence/internal/worker/autoscaler/RecommenderTest.java
+++ b/src/test/java/com/uber/cadence/internal/worker/autoscaler/RecommenderTest.java
@@ -18,10 +18,7 @@
 import static org.junit.Assert.*;
 
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class RecommenderTest {
 
   @Test
diff --git a/src/test/java/com/uber/cadence/internal/worker/autoscaler/ResizableSemaphoreTest.java b/src/test/java/com/uber/cadence/internal/worker/autoscaler/ResizableSemaphoreTest.java
index 13c9288d9..d5b09f780 100644
--- a/src/test/java/com/uber/cadence/internal/worker/autoscaler/ResizableSemaphoreTest.java
+++ b/src/test/java/com/uber/cadence/internal/worker/autoscaler/ResizableSemaphoreTest.java
@@ -18,10 +18,7 @@
 import static org.junit.Assert.*;
 
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
-@RunWith(MockitoJUnitRunner.class)
 public class ResizableSemaphoreTest {
 
   @Test
diff --git a/src/test/java/com/uber/cadence/migration/MigrationIWorkflowServiceTest.java b/src/test/java/com/uber/cadence/migration/MigrationIWorkflowServiceTest.java
index 92537aac2..163411976 100644
--- a/src/test/java/com/uber/cadence/migration/MigrationIWorkflowServiceTest.java
+++ b/src/test/java/com/uber/cadence/migration/MigrationIWorkflowServiceTest.java
@@ -27,7 +27,6 @@
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mock;
-import org.mockito.MockitoAnnotations;
 
 public class MigrationIWorkflowServiceTest {
 
@@ -38,7 +37,8 @@ public class MigrationIWorkflowServiceTest {
 
   @Before
   public void setUp() {
-    MockitoAnnotations.initMocks(this);
+    serviceOld = mock(IWorkflowService.class);
+    serviceNew = mock(IWorkflowService.class);
     migrationService =
         new MigrationIWorkflowService(serviceOld, "domainOld", serviceNew, "domainNew");
   }
diff --git a/src/test/java/com/uber/cadence/testing/WorkflowShadowerTest.java b/src/test/java/com/uber/cadence/testing/WorkflowShadowerTest.java
index 82d4cf7ac..06a532ea9 100644
--- a/src/test/java/com/uber/cadence/testing/WorkflowShadowerTest.java
+++ b/src/test/java/com/uber/cadence/testing/WorkflowShadowerTest.java
@@ -15,8 +15,8 @@
  */
 package com.uber.cadence.testing;
 
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.argThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -87,7 +87,7 @@ public void testRun_CallReplay_ThrowsException() throws Throwable {
   }
 
   private class ScanWorkflowActivityParamsMatcher
-      extends ArgumentMatcher<ScanWorkflowActivityParams> {
+      implements ArgumentMatcher<ScanWorkflowActivityParams> {
     ScanWorkflowActivityParams params;
 
     public ScanWorkflowActivityParamsMatcher(ScanWorkflowActivityParams params) {
@@ -95,7 +95,7 @@ public ScanWorkflowActivityParamsMatcher(ScanWorkflowActivityParams params) {
     }
 
     @Override
-    public boolean matches(Object argument) {
+    public boolean matches(ScanWorkflowActivityParams argument) {
       ScanWorkflowActivityParams newParams = (ScanWorkflowActivityParams) argument;
       return params.getDomain().equals(newParams.getDomain())
           && params.getWorkflowQuery().equals(newParams.getWorkflowQuery())
diff --git a/src/test/java/com/uber/cadence/worker/ShadowingWorkerTest.java b/src/test/java/com/uber/cadence/worker/ShadowingWorkerTest.java
index 8be2a91e6..7c338731a 100644
--- a/src/test/java/com/uber/cadence/worker/ShadowingWorkerTest.java
+++ b/src/test/java/com/uber/cadence/worker/ShadowingWorkerTest.java
@@ -16,8 +16,8 @@
  */
 package com.uber.cadence.worker;
 
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.argThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -103,7 +103,7 @@ public void testStartShadowingWorkflow_ReceiveExpectedRequest() throws Exception
   }
 
   private class StartWorkflowExecutionRequestMatcher
-      extends ArgumentMatcher<StartWorkflowExecutionRequest> {
+      implements ArgumentMatcher<StartWorkflowExecutionRequest> {
     StartWorkflowExecutionRequest request;
 
     public StartWorkflowExecutionRequestMatcher(StartWorkflowExecutionRequest request) {
@@ -111,7 +111,7 @@ public StartWorkflowExecutionRequestMatcher(StartWorkflowExecutionRequest reques
     }
 
     @Override
-    public boolean matches(Object argument) {
+    public boolean matches(StartWorkflowExecutionRequest argument) {
       StartWorkflowExecutionRequest newRequest = (StartWorkflowExecutionRequest) argument;
       return request.getDomain().equals(newRequest.getDomain())
           && request.getTaskList().equals(newRequest.getTaskList())
diff --git a/src/test/java/com/uber/cadence/worker/StickyWorkerTest.java b/src/test/java/com/uber/cadence/worker/StickyWorkerTest.java
index eaa79218f..2b7375580 100644
--- a/src/test/java/com/uber/cadence/worker/StickyWorkerTest.java
+++ b/src/test/java/com/uber/cadence/worker/StickyWorkerTest.java
@@ -21,8 +21,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
-import static org.mockito.Matchers.anyInt;
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
@@ -156,8 +155,8 @@ public void whenStickyIsEnabledThenTheWorkflowIsCachedSignals() throws Exception
             .build();
     Thread.sleep(600);
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyInt());
-    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyLong());
+    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyLong());
 
     // Finish Workflow
     wrapper.close();
@@ -269,8 +268,8 @@ public void whenStickyIsEnabledThenTheWorkflowIsCachedActivities() throws Except
             .put(MetricsTag.TASK_LIST, STICKY_TASK_LIST_METRIC_TAG)
             .build();
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyInt());
-    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyLong());
+    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyLong());
 
     // Finish Workflow
     wrapper.close();
@@ -318,8 +317,8 @@ public void whenStickyIsEnabledThenTheWorkflowIsCachedChildWorkflows() throws Ex
             .put(MetricsTag.TASK_LIST, STICKY_TASK_LIST_METRIC_TAG)
             .build();
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyInt());
-    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyLong());
+    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyLong());
     // Finish Workflow
     wrapper.close();
   }
@@ -374,8 +373,8 @@ public void whenStickyIsEnabledThenTheWorkflowIsCachedMutableSideEffect() throws
             .put(MetricsTag.TASK_LIST, STICKY_TASK_LIST_METRIC_TAG)
             .build();
     verify(reporter, atLeastOnce())
-        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyInt());
-    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyInt());
+        .reportCounter(eq(MetricsType.STICKY_CACHE_HIT), eq(tags), anyLong());
+    verify(reporter, never()).reportCounter(eq(MetricsType.STICKY_CACHE_MISS), eq(tags), anyLong());
     // Finish Workflow
     wrapper.close();
   }
diff --git a/src/test/java/com/uber/cadence/workflow/MetricsTest.java b/src/test/java/com/uber/cadence/workflow/MetricsTest.java
index 4b84a0919..a583e040e 100644
--- a/src/test/java/com/uber/cadence/workflow/MetricsTest.java
+++ b/src/test/java/com/uber/cadence/workflow/MetricsTest.java
@@ -19,8 +19,6 @@
 
 import static com.uber.cadence.testUtils.TestEnvironment.DOMAIN;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.*;
 
 import com.uber.cadence.activity.ActivityOptions;
diff --git a/src/test/java/com/uber/cadence/workflow/WorkflowTest.java b/src/test/java/com/uber/cadence/workflow/WorkflowTest.java
index 36576bb89..4535afd16 100644
--- a/src/test/java/com/uber/cadence/workflow/WorkflowTest.java
+++ b/src/test/java/com/uber/cadence/workflow/WorkflowTest.java
@@ -27,8 +27,6 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeTrue;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
 
 import com.google.common.base.Strings;
 import com.google.common.util.concurrent.UncheckedExecutionException;
@@ -5730,10 +5728,6 @@ public String getState() {
 
   @Test
   public void testGetVersionRetry() throws ExecutionException, InterruptedException {
-    TestActivities activity = mock(TestActivities.class);
-    when(activity.activity1(1)).thenReturn(1);
-    cadenceTestRule.getWorker().registerActivitiesImplementations(activity);
-
     startWorkerFor(TestGetVersionWorkflowRetryImpl.class);
     TestWorkflow3 workflowStub =
         workflowClient.newWorkflowStub(