The version where this SDK API was added.
@Since() annotation can be applied to a library declaration,
any public declaration in a library, or in a class, or to an optional
The returned version is "effective", so that if a library is annotated then all elements of the library inherit it; or if a class is annotated then all members and constructors of the class inherit it.
@Since() annotations apply to the same element, the latest
version takes precedence.
null if the element is not declared in SDK, or does not have
@Since() annotation applicable to it.
Version? get sinceSdkVersion;