public static double nonNegative(final double value, final String message) {
		if (value < 0) {
			throw new IllegalArgumentException(format(
				"%s must not be negative: %f.", message, value
			));
		}
		return value;
	}
Check if the specified value is not negative.

@param value the value to check.
@param message the exception message.
@return the given value.
@throws IllegalArgumentException if {@code value < 0}.
jenetics/src/main/java/io/jenetics/internal/util/Requires.java