Runtime.Version must be a value-based class

https://docs.oracle.com/javase/8/docs/api/java/lang/doc-files/ValueBased.html

TODO:

#1. Provide a similar paragraph as for other value-based classes:

     * <p>This is a <a href="./doc-files/ValueBased.html">value-based</a>
     * class; use of identity-sensitive operations (including reference equality
     * ({@code ==}), identity hash code, or synchronization) on instances of
     * {@code Version} may have unpredictable results and should be avoided.
     * </p>

#2. Restore lost `final` modifier for class
#3. Make constructor `final`
#4. Make `version` method return immutable lists rather than just unmodifiable