public static int nonNegative(final int length) {
		if (length < 0) {
			throw new NegativeArraySizeException(
				"Length must be greater than zero, but was " + length + ". "
			);
		}
		return length;
	}
Check if the given integer is negative.

@param length the value to check.
@return the length input
@throws NegativeArraySizeException if the given {@code length} is smaller
		  than zero.
jenetics/src/main/java/io/jenetics/internal/util/Requires.java