public static long sum(long[] array) {
		if (array == null) {
			return 0L;
		}
		long sum = 0;
		for (int i = 0; i < array.length; i++) {
			sum += array[i];
		}
		return sum;
	}
Concatenate {@code size} many values from the passed in arrays, starting at offset {@code start}.
spring-xd-analytics/src/main/java/org/springframework/xd/analytics/metrics/core/MetricUtils.java