Boxing of untyped literal; explicit boxing cast (@a/@d/@i/@int) recommended

An untyped literal was explicitly cast to the base type (Object) or passed to a method parameter of type System.Object and implicitly boxed, but the actual boxed value type may be unknown. We recommend explicitly casting the literal to the expected type using typed boxing casts (@d, @i, @a, @int, @decimal, etc). An explicit cast suppresses the warning.