8177738: Runtime.Version must be a value-based class
8148822: (spec) Regex in Runtime.Version and JEP 223 should match
8160954: (spec) Runtime.Version regex and $PRE/$OPT issues
8148877: (spec) Specify when an empty '+' is required in a version string
Reviewed-by: psandoz, rriggs
Contributed-by: Iris Clark <iris.clark@oracle.com>, Pavel Rappo <pavel.rappo@oracle.com>