diff --git a/pubsub/google/cloud/pubsub_v1/types.py b/pubsub/google/cloud/pubsub_v1/types.py
index f818d4aad80f..1b90bbb7dbbb 100644
--- a/pubsub/google/cloud/pubsub_v1/types.py
+++ b/pubsub/google/cloud/pubsub_v1/types.py
@@ -137,6 +137,39 @@
     )
 
 
+if sys.version_info >= (3, 5):
+    FlowControl.__doc__ = (
+        "The settings for controlling the rate at which messages are pulled "
+        "with an asynchronous subscription."
+    )
+    FlowControl.max_bytes.__doc__ = (
+        "The maximum total size of received - but not yet processed - messages "
+        "before pausing the message stream."
+    )
+    FlowControl.max_messages.__doc__ = (
+        "The maximum number of received - but not yet processed - messages before "
+        "pausing the message stream."
+    )
+    FlowControl.resume_threshold.__doc__ = (
+        "The relative threshold of the ``max_bytes`` and ``max_messages`` limits "
+        "below which to resume the message stream. Must be a positive number not "
+        "greater than ``1.0``."
+    )
+    FlowControl.max_requests.__doc__ = "Currently not in use."
+    FlowControl.max_request_batch_size.__doc__ = (
+        "The maximum number of requests scheduled by callbacks to process and "
+        "dispatch at a time."
+    )
+    FlowControl.max_request_batch_latency.__doc__ = (
+        "The maximum amount of time in seconds to wait for additional request "
+        "items before processing the next batch of requests."
+    )
+    FlowControl.max_lease_duration.__doc__ = (
+        "The maximum amount of time in seconds to hold a lease on a message "
+        "before dropping it from the lease management."
+    )
+
+
 _shared_modules = [
     http_pb2,
     iam_policy_pb2,
diff --git a/pubsub/synth.metadata b/pubsub/synth.metadata
index 09be1deb9f68..3838907bf04b 100644
--- a/pubsub/synth.metadata
+++ b/pubsub/synth.metadata
@@ -1,19 +1,19 @@
 {
-  "updateTime": "2019-06-18T12:24:16.486264Z",
+  "updateTime": "2019-06-19T12:19:44.898368Z",
   "sources": [
     {
       "generator": {
         "name": "artman",
-        "version": "0.27.0",
-        "dockerImage": "googleapis/artman@sha256:b036a7f4278d9deb5796f065e5c7f608d47d75369985ca7ab5039998120e972d"
+        "version": "0.28.0",
+        "dockerImage": "googleapis/artman@sha256:6ced5a36b08b82a328c69844e629300d58c14067f25cadab47f52542bdef7daf"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "384aa843867c4d17756d14a01f047b6368494d32",
-        "internalRef": "253675319"
+        "sha": "ac13167e31a20314aa05cc9911c95df250880485",
+        "internalRef": "253867808"
       }
     },
     {