public Builder addChannels(
        com.google.cloud.vertexai.api.SlackSource.SlackChannels.Builder builderForValue) {
      if (channelsBuilder_ == null) {
        ensureChannelsIsMutable();
        channels_.add(builderForValue.build());
        onChanged();
      } else {
        channelsBuilder_.addMessage(builderForValue.build());
      }
      return this;
    }
<pre>
Required. The Slack channels.
</pre>

<code>
repeated .google.cloud.vertexai.v1.SlackSource.SlackChannels channels = 1 [(.google.api.field_behavior) = REQUIRED];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/SlackSource.java