public static void ensure(String description, boolean condition) {
        if ( ! condition) {
            throw new IllegalArgumentException(description);
        }
    }
Ensures that the given argument is true

@param description of what is the case if the condition is false
@param condition the condition to ensure is true
@throws IllegalArgumentException if the given condition was false
vespajlib/src/main/java/com/yahoo/protect/Validator.java