@java.lang.Override
    public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
      getSerializedSize();
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(pubsubTopic_)) {
        com.google.protobuf.GeneratedMessageV3.writeString(output, 1, pubsubTopic_);
      }
      if (getEventTypesList().size() > 0) {
        output.writeUInt32NoTag(18);
        output.writeUInt32NoTag(eventTypesMemoizedSerializedSize);
      }
      for (int i = 0; i < eventTypes_.size(); i++) {
        output.writeEnumNoTag(eventTypes_.get(i));
      }
      if (payloadFormat_
          != com.google.storagetransfer.v1.proto.TransferTypes.NotificationConfig.PayloadFormat
              .PAYLOAD_FORMAT_UNSPECIFIED
              .getNumber()) {
        output.writeEnum(3, payloadFormat_);
      }
      getUnknownFields().writeTo(output);
    }
<pre>
Required. The desired format of the notification message payloads.
</pre>

<code>
.google.storagetransfer.v1.NotificationConfig.PayloadFormat payload_format = 3 [(.google.api.field_behavior) = REQUIRED];
</code>

@return The payloadFormat.
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java