public com.google.protobuf.ByteString getNextPageTokenBytes() {
      java.lang.Object ref = nextPageToken_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        nextPageToken_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
A token identifying a page of results the server should return.
</pre>

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

@return The bytes for nextPageToken.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/ListEventsResponse.java