Mutation testing for condition that does not affect return

Question

I’m running a pit mutation test for my function and I can’t seem to cover this line for the negated conditional. So it’s a if statement that does a substring to build a url for the service call.

public List<Player> retrievePlayers(List<String> playerIds) throws error {


    List<Player> players = new ArrayList<Player>();

    ResponseEntity<String> playerDetails;

    String currentPlayerId = null;

    for(String playerId : playerIds) {
        currentPlayerId = playerId;

        if (playerId.length() == 15) { 
            currentPlayerId = playerId.substring(0,10); 
        }
    }

    try {
        playerDetails = playerFetchDelegate.getPlayerDetails(currentPlayerId);
        convertResponseToObject(playerDetails, players);
    } catch (exception) {
        throw new exception
    }

    }
    return players;
}

So the mutation is not covering the if statement because the condition doesn’t change the return. How can I cover the line?

Thanks!