public com.google.protobuf.Timestamp.Builder getStartTimeBuilder() {
      bitField0_ |= 0x00000010;
      onChanged();
      return getStartTimeFieldBuilder().getBuilder();
    }
<pre>
Start of the time interval (inclusive) during which the trace data was
collected from the application.
</pre>

<code>.google.protobuf.Timestamp start_time = 5;</code>
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/ListTracesRequest.java