private void ensureEventTypesIsMutable() {
        if (!((bitField0_ & 0x00000002) != 0)) {
          eventTypes_ = new java.util.ArrayList<java.lang.Integer>(eventTypes_);
          bitField0_ |= 0x00000002;
        }
      }
<pre>
Required. The `Topic.name` of the Pub/Sub topic to which to publish
notifications. Must be of the format: `projects/{project}/topics/{topic}`.
Not matching this format results in an
[INVALID_ARGUMENT][google.rpc.Code.INVALID_ARGUMENT] error.
</pre>

<code>string pubsub_topic = 1 [(.google.api.field_behavior) = REQUIRED];</code>

@param value The bytes for pubsubTopic to set.
@return This builder for chaining.
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java