@java.lang.Override
      public int getSerializedSize() {
        int size = memoizedSize;
        if (size != -1) return size;

        size = 0;
        if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(channelId_)) {
          size += com.google.protobuf.GeneratedMessageV3.computeStringSize(1, channelId_);
        }
        if (((bitField0_ & 0x00000001) != 0)) {
          size += com.google.protobuf.CodedOutputStream.computeMessageSize(2, getStartTime());
        }
        if (((bitField0_ & 0x00000002) != 0)) {
          size += com.google.protobuf.CodedOutputStream.computeMessageSize(3, getEndTime());
        }
        size += getUnknownFields().getSerializedSize();
        memoizedSize = size;
        return size;
      }
<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