@java.lang.Override
      public com.google.protobuf.Timestamp getStartTime() {
        return startTime_ == null ? com.google.protobuf.Timestamp.getDefaultInstance() : startTime_;
      }
<pre>
Optional. The starting timestamp for messages to import.
</pre>

<code>.google.protobuf.Timestamp start_time = 2 [(.google.api.field_behavior) = OPTIONAL];
</code>

@return The startTime.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/SlackSource.java