diff --git a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockAlertPolicyServiceImpl.java b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockAlertPolicyServiceImpl.java
index 9e18fc94a5cc..6fec82cdf8a0 100644
--- a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockAlertPolicyServiceImpl.java
+++ b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockAlertPolicyServiceImpl.java
@@ -35,7 +35,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockAlertPolicyServiceImpl extends AlertPolicyServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockAlertPolicyServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockGroupServiceImpl.java b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockGroupServiceImpl.java
index 129420b2396e..f53588b542ae 100644
--- a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockGroupServiceImpl.java
+++ b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockGroupServiceImpl.java
@@ -37,7 +37,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockGroupServiceImpl extends GroupServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockGroupServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockMetricServiceImpl.java b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockMetricServiceImpl.java
index 83707b3731cb..9a75d1f91e12 100644
--- a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockMetricServiceImpl.java
+++ b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockMetricServiceImpl.java
@@ -41,7 +41,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockMetricServiceImpl extends MetricServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockMetricServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockNotificationChannelServiceImpl.java b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockNotificationChannelServiceImpl.java
index b1fd26f329d8..572718d5a702 100644
--- a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockNotificationChannelServiceImpl.java
+++ b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockNotificationChannelServiceImpl.java
@@ -39,7 +39,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockNotificationChannelServiceImpl extends NotificationChannelServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockNotificationChannelServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockUptimeCheckServiceImpl.java b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockUptimeCheckServiceImpl.java
index f463929030fa..1ade4591695c 100644
--- a/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockUptimeCheckServiceImpl.java
+++ b/google-cloud-clients/google-cloud-monitoring/src/test/java/com/google/cloud/monitoring/v3/MockUptimeCheckServiceImpl.java
@@ -37,7 +37,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockUptimeCheckServiceImpl extends UptimeCheckServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockUptimeCheckServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-monitoring/synth.metadata b/google-cloud-clients/google-cloud-monitoring/synth.metadata
index dc4c0c0a4ba1..0bb1f60e87f6 100644
--- a/google-cloud-clients/google-cloud-monitoring/synth.metadata
+++ b/google-cloud-clients/google-cloud-monitoring/synth.metadata
@@ -1,19 +1,19 @@
 {
-  "updateTime": "2019-03-29T07:50:35.516882Z",
+  "updateTime": "2019-04-02T07:50:28.005059Z",
   "sources": [
     {
       "generator": {
         "name": "artman",
-        "version": "0.16.21",
-        "dockerImage": "googleapis/artman@sha256:854131ec1af7b3a313253474c24748dc0acd217a58a0b74dbfb559f340a15d78"
+        "version": "0.16.22",
+        "dockerImage": "googleapis/artman@sha256:e7f9554322a8aa1416c122c918fdc4cdec8cfe816f027fc948dec0be7edef320"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "37386f1ebcaed51bcb7d15d00124d22c38606e45",
-        "internalRef": "240841842"
+        "sha": "6c48ab5aef47dc14e02e2dc718d232a28067129d",
+        "internalRef": "241437588"
       }
     }
   ],