public com.google.protobuf.Timestamp getStartTime() {
          if (startTimeBuilder_ == null) {
            return startTime_ == null
                ? com.google.protobuf.Timestamp.getDefaultInstance()
                : startTime_;
          } else {
            return startTimeBuilder_.getMessage();
          }
        }
<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