Finding an equilibrium index in an int array

getEquilibrium.java

public int getEquilibrium(int[] array) {
    long totalSum = sum(array);
    long lowSum = 0L;
    for (int i = 0; i < array.length; i++) {
        totalSum -= array[i];
        if (lowSum == totalSum) {
            return i;
        }
        lowSum += array[i];
    }
    return -1;
}

public long sum(int[] array) {
    return Arrays.stream(array).asLongStream().sum();
}