@Override
    public StateIdsBuilder append(final String stateToken, final int document) {
        return doAppend(Collections.singletonList(new StateId(stateToken, document)));
    }
@ Override public StateIdsBuilder append ( final String stateToken , final int document ) { return doAppend ( Collections . singletonList ( new StateId ( stateToken , document ) ) ) ; }
Appends the specified state token and a single zero-based document index to this instance, returning
{@code this}.

@param stateToken The state token to append
@param document The document index for the state token
@return {@code this}