@java.lang.Override
  public Builder toBuilder() {
    return this == DEFAULT_INSTANCE ? new Builder() : new Builder().mergeFrom(this);
  }
<pre>
If defined, indicates that there are more traces that match the request
and that this value should be passed to the next request to continue
retrieving additional traces.
</pre>

<code>string next_page_token = 2;</code>

@return The bytes for nextPageToken.
java-trace/proto-google-cloud-trace-v1/src/main/java/com/google/devtools/cloudtrace/v1/ListTracesResponse.java