@java.lang.Override
      public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
        if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(channelId_)) {
          com.google.protobuf.GeneratedMessageV3.writeString(output, 1, channelId_);
        }
        if (((bitField0_ & 0x00000001) != 0)) {
          output.writeMessage(2, getStartTime());
        }
        if (((bitField0_ & 0x00000002) != 0)) {
          output.writeMessage(3, getEndTime());
        }
        getUnknownFields().writeTo(output);
      }
<pre>
Optional. The ending timestamp for messages to import.
</pre>

<code>.google.protobuf.Timestamp end_time = 3 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/SlackSource.java