public java.lang.String getNextPageToken() {
      java.lang.Object ref = nextPageToken_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        nextPageToken_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
Optional. Token to retrieve the next page of results, or empty if there are
no more results in the list.
</pre>

<code>string next_page_token = 2 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The nextPageToken.
java-workstations/proto-google-cloud-workstations-v1beta/src/main/java/com/google/cloud/workstations/v1beta/ListWorkstationsResponse.java