Consider the ArrayUpdater class shown above. If two threads simultaneously call the fill method on the same ArrayUpdater object with different arguments for value, which concurrency issue is most likely to occur?

public class ArrayUpdater {
    private int[][] data = new int[4][4];

    public void fill(int value) {
        for (int i = 0; i < data.length; i++)
            for (int j = 0; j < data[i].length; j++)
                data[i][j] = value;
    }

    public int[][] getData() {
        return data;
    }

    public static void main(String[] args) {
        ArrayUpdater updater = new ArrayUpdater();
        Thread t1 = new Thread(() -> updater.fill(1));
        Thread t2 = new Thread(() -> updater.fill(2));
        t1.start();
        t2.start();
    }
}