diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockClusterControllerImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockClusterControllerImpl.java
index 7781c102a25d..93a5d3b2bdb4 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockClusterControllerImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockClusterControllerImpl.java
@@ -28,7 +28,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockClusterControllerImpl extends ClusterControllerImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockClusterControllerImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockJobControllerImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockJobControllerImpl.java
index 233d57a537f3..df89cb20d877 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockJobControllerImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockJobControllerImpl.java
@@ -28,7 +28,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockJobControllerImpl extends JobControllerImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockJobControllerImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockWorkflowTemplateServiceImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockWorkflowTemplateServiceImpl.java
index 82fad23e48aa..a07e7119f3cf 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockWorkflowTemplateServiceImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1/MockWorkflowTemplateServiceImpl.java
@@ -29,7 +29,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockWorkflowTemplateServiceImpl extends WorkflowTemplateServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockWorkflowTemplateServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockClusterControllerImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockClusterControllerImpl.java
index 0243f55d921c..490a6f013c7a 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockClusterControllerImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockClusterControllerImpl.java
@@ -28,7 +28,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockClusterControllerImpl extends ClusterControllerImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockClusterControllerImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockJobControllerImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockJobControllerImpl.java
index 44e55008ed95..8bf14d19cc70 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockJobControllerImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockJobControllerImpl.java
@@ -28,7 +28,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockJobControllerImpl extends JobControllerImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockJobControllerImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockWorkflowTemplateServiceImpl.java b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockWorkflowTemplateServiceImpl.java
index 123bc68f6ee1..12c0cd549957 100644
--- a/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockWorkflowTemplateServiceImpl.java
+++ b/google-cloud-clients/google-cloud-dataproc/src/test/java/com/google/cloud/dataproc/v1beta2/MockWorkflowTemplateServiceImpl.java
@@ -29,7 +29,7 @@
 @javax.annotation.Generated("by GAPIC")
 @BetaApi
 public class MockWorkflowTemplateServiceImpl extends WorkflowTemplateServiceImplBase {
-  private ArrayList<AbstractMessage> requests;
+  private List<AbstractMessage> requests;
   private Queue<Object> responses;
 
   public MockWorkflowTemplateServiceImpl() {
diff --git a/google-cloud-clients/google-cloud-dataproc/synth.metadata b/google-cloud-clients/google-cloud-dataproc/synth.metadata
index f17dc4065e90..98c322235e1b 100644
--- a/google-cloud-clients/google-cloud-dataproc/synth.metadata
+++ b/google-cloud-clients/google-cloud-dataproc/synth.metadata
@@ -1,19 +1,19 @@
 {
-  "updateTime": "2019-03-29T07:40:41.335140Z",
+  "updateTime": "2019-04-02T07:40:46.876896Z",
   "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"
       }
     }
   ],