diff --git a/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/LoggingServiceV2Settings.java b/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/LoggingServiceV2Settings.java
index adf9ee22181f..08a31bafc375 100644
--- a/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/LoggingServiceV2Settings.java
+++ b/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/LoggingServiceV2Settings.java
@@ -20,11 +20,15 @@
 import static com.google.cloud.logging.spi.v2.PagedResponseWrappers.ListMonitoredResourceDescriptorsPagedResponse;
 
 import com.google.api.MonitoredResourceDescriptor;
+import com.google.api.gax.bundling.BundlingSettings;
+import com.google.api.gax.bundling.RequestBuilder;
+import com.google.api.gax.core.FlowControlSettings;
+import com.google.api.gax.core.FlowController.LimitExceededBehavior;
 import com.google.api.gax.core.GoogleCredentialsProvider;
 import com.google.api.gax.core.RetrySettings;
+import com.google.api.gax.grpc.BundledRequestIssuer;
 import com.google.api.gax.grpc.BundlingCallSettings;
 import com.google.api.gax.grpc.BundlingDescriptor;
-import com.google.api.gax.grpc.BundlingSettings;
 import com.google.api.gax.grpc.CallContext;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ClientSettings;
@@ -34,7 +38,6 @@
 import com.google.api.gax.grpc.PagedCallSettings;
 import com.google.api.gax.grpc.PagedListDescriptor;
 import com.google.api.gax.grpc.PagedListResponseFactory;
-import com.google.api.gax.grpc.RequestIssuer;
 import com.google.api.gax.grpc.SimpleCallSettings;
 import com.google.api.gax.grpc.UnaryCallSettings;
 import com.google.api.gax.grpc.UnaryCallable;
@@ -58,9 +61,7 @@
 import com.google.protobuf.ExperimentalApi;
 import io.grpc.Status;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collection;
-import java.util.List;
 import javax.annotation.Generated;
 import org.joda.time.Duration;
 
@@ -398,33 +399,32 @@ public String getBundlePartitionKey(WriteLogEntriesRequest request) {
             }
 
             @Override
-            public WriteLogEntriesRequest mergeRequests(
-                Collection<WriteLogEntriesRequest> requests) {
-              WriteLogEntriesRequest firstRequest = requests.iterator().next();
-
-              List<LogEntry> elements = new ArrayList<>();
-              for (WriteLogEntriesRequest request : requests) {
-                elements.addAll(request.getEntriesList());
-              }
-
-              WriteLogEntriesRequest bundleRequest =
-                  WriteLogEntriesRequest.newBuilder()
-                      .setLogName(firstRequest.getLogName())
-                      .setResource(firstRequest.getResource())
-                      .putAllLabels(firstRequest.getLabels())
-                      .addAllEntries(elements)
-                      .build();
-              return bundleRequest;
+            public RequestBuilder<WriteLogEntriesRequest> getRequestBuilder() {
+              return new RequestBuilder<WriteLogEntriesRequest>() {
+                private WriteLogEntriesRequest.Builder builder;
+
+                @Override
+                public void appendRequest(WriteLogEntriesRequest request) {
+                  if (builder == null) {
+                    builder = request.toBuilder();
+                  } else {
+                    builder.addAllEntries(request.getEntriesList());
+                  }
+                }
+
+                @Override
+                public WriteLogEntriesRequest build() {
+                  return builder.build();
+                }
+              };
             }
 
             @Override
             public void splitResponse(
                 WriteLogEntriesResponse bundleResponse,
-                Collection<? extends RequestIssuer<WriteLogEntriesRequest, WriteLogEntriesResponse>>
-                    bundle) {
+                Collection<? extends BundledRequestIssuer<WriteLogEntriesResponse>> bundle) {
               int bundleMessageIndex = 0;
-              for (RequestIssuer<WriteLogEntriesRequest, WriteLogEntriesResponse> responder :
-                  bundle) {
+              for (BundledRequestIssuer<WriteLogEntriesResponse> responder : bundle) {
                 WriteLogEntriesResponse response = WriteLogEntriesResponse.newBuilder().build();
                 responder.setResponse(response);
               }
@@ -433,10 +433,8 @@ public void splitResponse(
             @Override
             public void splitException(
                 Throwable throwable,
-                Collection<? extends RequestIssuer<WriteLogEntriesRequest, WriteLogEntriesResponse>>
-                    bundle) {
-              for (RequestIssuer<WriteLogEntriesRequest, WriteLogEntriesResponse> responder :
-                  bundle) {
+                Collection<? extends BundledRequestIssuer<WriteLogEntriesResponse>> bundle) {
+              for (BundledRequestIssuer<WriteLogEntriesResponse> responder : bundle) {
                 responder.setException(throwable);
               }
             }
@@ -556,9 +554,15 @@ private static Builder createDefault() {
       builder
           .writeLogEntriesSettings()
           .getBundlingSettingsBuilder()
-          .setElementCountThreshold(100)
-          .setRequestByteThreshold(1024)
-          .setDelayThreshold(Duration.millis(10));
+          .setElementCountThreshold(1000)
+          .setRequestByteThreshold(1048576)
+          .setDelayThreshold(Duration.millis(50))
+          .setFlowControlSettings(
+              FlowControlSettings.newBuilder()
+                  .setMaxOutstandingElementCount(100000)
+                  .setMaxOutstandingRequestBytes(10485760)
+                  .setLimitExceededBehavior(LimitExceededBehavior.ThrowException)
+                  .build());
       builder
           .writeLogEntriesSettings()
           .setRetryableCodes(RETRYABLE_CODE_DEFINITIONS.get("non_idempotent"))
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/MessageDispatcher.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/MessageDispatcher.java
index c43f03bc1c6b..ce0bd5c8cc49 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/MessageDispatcher.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/MessageDispatcher.java
@@ -16,7 +16,7 @@
 
 package com.google.cloud.pubsub.spi.v1;
 
-import com.google.api.gax.grpc.FlowController;
+import com.google.api.gax.core.FlowController;
 import com.google.api.stats.Distribution;
 import com.google.cloud.Clock;
 import com.google.common.annotations.VisibleForTesting;
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PollingSubscriberConnection.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PollingSubscriberConnection.java
index 2c3b6d7fa84c..e2a8073f431f 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PollingSubscriberConnection.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PollingSubscriberConnection.java
@@ -18,7 +18,7 @@
 
 import static com.google.cloud.pubsub.spi.v1.StatusUtil.isRetryable;
 
-import com.google.api.gax.grpc.FlowController;
+import com.google.api.gax.core.FlowController;
 import com.google.api.stats.Distribution;
 import com.google.auth.Credentials;
 import com.google.cloud.Clock;
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Publisher.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Publisher.java
index ebb0329d9b12..9ba3bfe928ca 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Publisher.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Publisher.java
@@ -16,16 +16,16 @@
 
 package com.google.cloud.pubsub.spi.v1;
 
+import com.google.api.gax.bundling.BundlingSettings;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.core.ApiFutureCallback;
 import com.google.api.gax.core.ApiFutures;
+import com.google.api.gax.core.FlowControlSettings;
+import com.google.api.gax.core.FlowController;
 import com.google.api.gax.core.Function;
 import com.google.api.gax.core.RetrySettings;
-import com.google.api.gax.grpc.BundlingSettings;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ExecutorProvider;
-import com.google.api.gax.grpc.FlowControlSettings;
-import com.google.api.gax.grpc.FlowController;
 import com.google.api.gax.grpc.InstantiatingExecutorProvider;
 import com.google.auth.oauth2.GoogleCredentials;
 import com.google.common.annotations.VisibleForTesting;
@@ -88,7 +88,6 @@ public class Publisher {
   private final LongRandom longRandom;
 
   private final FlowControlSettings flowControlSettings;
-  private final boolean failOnFlowControlLimits;
 
   private final Lock messagesBundleLock;
   private List<OutstandingPublish> messagesBundle;
@@ -125,8 +124,7 @@ private Publisher(Builder builder) throws IOException {
     this.longRandom = builder.longRandom;
 
     flowControlSettings = builder.flowControlSettings;
-    failOnFlowControlLimits = builder.failOnFlowControlLimits;
-    this.flowController = new FlowController(flowControlSettings, failOnFlowControlLimits);
+    this.flowController = new FlowController(flowControlSettings);
 
     messagesBundle = new LinkedList<>();
     messagesBundleLock = new ReentrantLock();
@@ -173,12 +171,14 @@ public TopicName getTopicName() {
    * Schedules the publishing of a message. The publishing of the message may occur immediately or
    * be delayed based on the publisher bundling options.
    *
-   * <p>Depending on chosen flow control {@link #failOnFlowControlLimits option}, the returned
-   * future might immediately fail with a {@link com.google.api.gax.grpc.FlowController.FlowControlException}
-   * or block the current thread until there are more resources available to publish.
+   * <p>Depending on chosen flow control {@link FlowControlSettings#getLimitExceededBehavior
+   * option}, the returned future might immediately fail with a {@link
+   * FlowController.FlowControlException} or block the current thread until there are more resources
+   * available to publish.
    *
    * <p>Example of publishing a message.
-   * <pre> {@code
+   *
+   * <pre>{@code
    * String message = "my_message";
    * ByteString data = ByteString.copyFromUtf8(message);
    * PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
@@ -473,26 +473,19 @@ private long getMaxBundleBytes() {
   }
 
   /**
-   * The bundling settings configured on this {@code Publisher}. See {@link
-   * #failOnFlowControlLimits()}.
+   * The bundling settings configured on this {@code Publisher}, including whether to block publish
+   * calls when reaching flow control limits.
+   *
+   * <p>If {@link FlowControlSettings#getLimitExceededBehavior()} is set to {@link
+   * FlowController.LimitExceededBehavior#ThrowException}, a publish call will fail with either
+   * {@link FlowController.MaxOutstandingRequestBytesReachedException} or {@link
+   * FlowController.MaxOutstandingElementCountReachedException}, as appropriate, when flow control
+   * limits are reached.
    */
   public FlowControlSettings getFlowControlSettings() {
     return flowControlSettings;
   }
 
-  /**
-   * Whether to block publish calls when reaching flow control limits (see {@link
-   * #getFlowControlSettings()}).
-   *
-   * <p>If set to false, a publish call will fail with either {@link
-   * com.google.api.gax.grpc.FlowController.MaxOutstandingRequestBytesReachedException} or {@link
-   * com.google.api.gax.grpc.FlowController.MaxOutstandingElementCountReachedException}, as
-   * appropriate, when flow contro limits are reached.
-   */
-  public boolean failOnFlowControlLimits() {
-    return failOnFlowControlLimits;
-  }
-
   /**
    * Schedules immediate publishing of any outstanding messages and waits until all are processed.
    *
@@ -619,7 +612,6 @@ public long nextLong(long least, long bound) {
 
     // Client-side flow control options
     FlowControlSettings flowControlSettings = FlowControlSettings.getDefaultInstance();
-    boolean failOnFlowControlLimits;
 
     RetrySettings retrySettings = DEFAULT_RETRY_SETTINGS;
     LongRandom longRandom = DEFAULT_LONG_RANDOM;
@@ -665,20 +657,6 @@ public Builder setFlowControlSettings(FlowControlSettings flowControlSettings) {
       return this;
     }
 
-    /**
-     * Whether to fail publish when reaching any of the flow control limits, with either a {@link
-     * com.google.api.gax.grpc.FlowController.MaxOutstandingRequestBytesReachedException} or {@link
-     * com.google.api.gax.grpc.FlowController.MaxOutstandingElementCountReachedException} as
-     * appropriate.
-     *
-     * <p>If set to false, then publish operations will block the current thread until the
-     * outstanding requests go under the limits.
-     */
-    public Builder setFailOnFlowControlLimits(boolean fail) {
-      failOnFlowControlLimits = fail;
-      return this;
-    }
-
     /** Configures the Publisher's retry parameters. */
     public Builder setRetrySettings(RetrySettings retrySettings) {
       Preconditions.checkArgument(
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PublisherSettings.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PublisherSettings.java
index 535487c4a7f3..82813efbfef5 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PublisherSettings.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/PublisherSettings.java
@@ -18,11 +18,15 @@
 import static com.google.cloud.pubsub.spi.v1.PagedResponseWrappers.ListTopicSubscriptionsPagedResponse;
 import static com.google.cloud.pubsub.spi.v1.PagedResponseWrappers.ListTopicsPagedResponse;
 
+import com.google.api.gax.bundling.BundlingSettings;
+import com.google.api.gax.bundling.RequestBuilder;
+import com.google.api.gax.core.FlowControlSettings;
+import com.google.api.gax.core.FlowController.LimitExceededBehavior;
 import com.google.api.gax.core.GoogleCredentialsProvider;
 import com.google.api.gax.core.RetrySettings;
+import com.google.api.gax.grpc.BundledRequestIssuer;
 import com.google.api.gax.grpc.BundlingCallSettings;
 import com.google.api.gax.grpc.BundlingDescriptor;
-import com.google.api.gax.grpc.BundlingSettings;
 import com.google.api.gax.grpc.CallContext;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ClientSettings;
@@ -32,7 +36,6 @@
 import com.google.api.gax.grpc.PagedCallSettings;
 import com.google.api.gax.grpc.PagedListDescriptor;
 import com.google.api.gax.grpc.PagedListResponseFactory;
-import com.google.api.gax.grpc.RequestIssuer;
 import com.google.api.gax.grpc.SimpleCallSettings;
 import com.google.api.gax.grpc.UnaryCallSettings;
 import com.google.api.gax.grpc.UnaryCallable;
@@ -58,7 +61,6 @@
 import com.google.pubsub.v1.PublishRequest;
 import com.google.pubsub.v1.PublishResponse;
 import com.google.pubsub.v1.PublisherGrpc;
-import com.google.pubsub.v1.PubsubMessage;
 import com.google.pubsub.v1.Topic;
 import io.grpc.Status;
 import java.io.IOException;
@@ -363,30 +365,34 @@ public String getBundlePartitionKey(PublishRequest request) {
         }
 
         @Override
-        public PublishRequest mergeRequests(Collection<PublishRequest> requests) {
-          PublishRequest firstRequest = requests.iterator().next();
+        public RequestBuilder<PublishRequest> getRequestBuilder() {
+          return new RequestBuilder<PublishRequest>() {
+            private PublishRequest.Builder builder;
 
-          List<PubsubMessage> elements = new ArrayList<>();
-          for (PublishRequest request : requests) {
-            elements.addAll(request.getMessagesList());
-          }
+            @Override
+            public void appendRequest(PublishRequest request) {
+              if (builder == null) {
+                builder = request.toBuilder();
+              } else {
+                builder.addAllMessages(request.getMessagesList());
+              }
+            }
 
-          PublishRequest bundleRequest =
-              PublishRequest.newBuilder()
-                  .setTopic(firstRequest.getTopic())
-                  .addAllMessages(elements)
-                  .build();
-          return bundleRequest;
+            @Override
+            public PublishRequest build() {
+              return builder.build();
+            }
+          };
         }
 
         @Override
         public void splitResponse(
             PublishResponse bundleResponse,
-            Collection<? extends RequestIssuer<PublishRequest, PublishResponse>> bundle) {
+            Collection<? extends BundledRequestIssuer<PublishResponse>> bundle) {
           int bundleMessageIndex = 0;
-          for (RequestIssuer<PublishRequest, PublishResponse> responder : bundle) {
+          for (BundledRequestIssuer<PublishResponse> responder : bundle) {
             List<String> subresponseElements = new ArrayList<>();
-            int subresponseCount = responder.getRequest().getMessagesCount();
+            long subresponseCount = responder.getMessageCount();
             for (int i = 0; i < subresponseCount; i++) {
               subresponseElements.add(bundleResponse.getMessageIds(bundleMessageIndex));
               bundleMessageIndex += 1;
@@ -400,8 +406,8 @@ public void splitResponse(
         @Override
         public void splitException(
             Throwable throwable,
-            Collection<? extends RequestIssuer<PublishRequest, PublishResponse>> bundle) {
-          for (RequestIssuer<PublishRequest, PublishResponse> responder : bundle) {
+            Collection<? extends BundledRequestIssuer<PublishResponse>> bundle) {
+          for (BundledRequestIssuer<PublishResponse> responder : bundle) {
             responder.setException(throwable);
           }
         }
@@ -539,7 +545,11 @@ private static Builder createDefault() {
           .getBundlingSettingsBuilder()
           .setElementCountThreshold(10)
           .setRequestByteThreshold(1024)
-          .setDelayThreshold(Duration.millis(10));
+          .setDelayThreshold(Duration.millis(10))
+          .setFlowControlSettings(
+              FlowControlSettings.newBuilder()
+                  .setLimitExceededBehavior(LimitExceededBehavior.Ignore)
+                  .build());
       builder
           .publishSettings()
           .setRetryableCodes(RETRYABLE_CODE_DEFINITIONS.get("one_plus_delivery"))
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/StreamingSubscriberConnection.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/StreamingSubscriberConnection.java
index 8f2d121b3e6e..7c3a6a8b7c4b 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/StreamingSubscriberConnection.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/StreamingSubscriberConnection.java
@@ -18,7 +18,7 @@
 
 import static com.google.cloud.pubsub.spi.v1.StatusUtil.isRetryable;
 
-import com.google.api.gax.grpc.FlowController;
+import com.google.api.gax.core.FlowController;
 import com.google.api.stats.Distribution;
 import com.google.auth.Credentials;
 import com.google.cloud.Clock;
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java
index 902226db408f..8133e4829a68 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java
@@ -16,9 +16,9 @@
 
 package com.google.cloud.pubsub.spi.v1;
 
+import com.google.api.gax.core.FlowControlSettings;
+import com.google.api.gax.core.FlowController;
 import com.google.api.gax.grpc.ExecutorProvider;
-import com.google.api.gax.grpc.FlowControlSettings;
-import com.google.api.gax.grpc.FlowController;
 import com.google.api.gax.grpc.InstantiatingExecutorProvider;
 import com.google.api.stats.Distribution;
 import com.google.auth.Credentials;
@@ -283,7 +283,7 @@ private SubscriberImpl(Builder builder) throws IOException {
               Ints.saturatedCast(ackExpirationPadding.getStandardSeconds()));
       clock = builder.clock.isPresent() ? builder.clock.get() : Clock.defaultClock();
 
-      flowController = new FlowController(builder.flowControlSettings, false);
+      flowController = new FlowController(builder.flowControlSettings);
 
       executor = builder.executorProvider.getExecutor();
       if (builder.executorProvider.shouldAutoClose()) {
diff --git a/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/PublisherImplTest.java b/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/PublisherImplTest.java
index c4c919fc04dd..8a96e8823928 100644
--- a/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/PublisherImplTest.java
+++ b/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/PublisherImplTest.java
@@ -18,17 +18,17 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.atLeast;
 import static org.mockito.Mockito.times;
 
-import com.google.api.gax.grpc.BundlingSettings;
+import com.google.api.gax.bundling.BundlingSettings;
+import com.google.api.gax.core.FlowControlSettings;
+import com.google.api.gax.core.FlowController.LimitExceededBehavior;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ExecutorProvider;
 import com.google.api.gax.grpc.FixedExecutorProvider;
-import com.google.api.gax.grpc.FlowControlSettings;
 import com.google.api.gax.grpc.InstantiatingExecutorProvider;
 import com.google.cloud.pubsub.spi.v1.Publisher.Builder;
 import com.google.protobuf.ByteString;
@@ -372,7 +372,6 @@ public void testPublisherGetters() throws Exception {
     Publisher.Builder builder = Publisher.newBuilder(TEST_TOPIC);
     builder.setChannelProvider(TEST_CHANNEL_PROVIDER);
     builder.setExecutorProvider(SINGLE_THREAD_EXECUTOR);
-    builder.setFailOnFlowControlLimits(true);
     builder.setBundlingSettings(
         BundlingSettings.newBuilder()
             .setRequestByteThreshold(10)
@@ -383,6 +382,7 @@ public void testPublisherGetters() throws Exception {
         FlowControlSettings.newBuilder()
             .setMaxOutstandingRequestBytes(13)
             .setMaxOutstandingElementCount(14)
+            .setLimitExceededBehavior(LimitExceededBehavior.ThrowException)
             .build());
     Publisher publisher = builder.build();
 
@@ -392,7 +392,9 @@ public void testPublisherGetters() throws Exception {
     assertEquals(12, (long) publisher.getBundlingSettings().getElementCountThreshold());
     assertEquals(13, (long) publisher.getFlowControlSettings().getMaxOutstandingRequestBytes());
     assertEquals(14, (long) publisher.getFlowControlSettings().getMaxOutstandingElementCount());
-    assertTrue(publisher.failOnFlowControlLimits());
+    assertEquals(
+        LimitExceededBehavior.ThrowException,
+        publisher.getFlowControlSettings().getLimitExceededBehavior());
     publisher.shutdown();
   }
 
@@ -401,7 +403,8 @@ public void testBuilderParametersAndDefaults() {
     Publisher.Builder builder = Publisher.newBuilder(TEST_TOPIC);
     assertEquals(TEST_TOPIC, builder.topicName);
     assertEquals(Publisher.Builder.DEFAULT_EXECUTOR_PROVIDER, builder.executorProvider);
-    assertFalse(builder.failOnFlowControlLimits);
+    assertEquals(
+        LimitExceededBehavior.Block, builder.flowControlSettings.getLimitExceededBehavior());
     assertEquals(
         Publisher.Builder.DEFAULT_REQUEST_BYTES_THRESHOLD,
         builder.bundlingSettings.getRequestByteThreshold().longValue());
diff --git a/pom.xml b/pom.xml
index ee844891e030..207164f29494 100644
--- a/pom.xml
+++ b/pom.xml
@@ -92,7 +92,7 @@
     <github.global.server>github</github.global.server>
     <google.auth.version>0.6.0</google.auth.version>
     <grpc.version>1.0.3</grpc.version>
-    <gax.version>0.2.0</gax.version>
+    <gax.version>0.3.0</gax.version>
     <generatedProto.version>0.1.5</generatedProto.version>
     <core.version>0.9.5-alpha-SNAPSHOT</core.version>
     <beta.version>0.9.5-beta-SNAPSHOT</beta.version>