Method isValid

base/src/main/java/net/time4j/Weekmodel.java:1256–1273

(
            T context,
            Weekday value
        )

        }

        @Override
        public boolean isValid(
            T context,
            Weekday value
        ) {

            if (value == null) {
                return false;
            }

            try {
                this.withValue(context, value, false);
                return true;
            } catch (ArithmeticException | IllegalArgumentException ex) {
                return false;
            }

        }

        @Override
        public T withValue(