@Documented @Retention(value=RUNTIME) @Target(value={TYPE_USE,TYPE_PARAMETER}) @SubtypeOf(value=UnknownRegex.class) public @interface Regex
@Regex(n), then the run-time value is a regular expression with
 n capturing groups.
 For example, if an expression's type is @Regex(2) String, then at run time its value
 will be a legal regular expression with at least two capturing groups. The type states that
 possible run-time values include "(a*)(b*)", "a(b?)c(d?)e", and "(.)(.)(.)", but not "hello" nor "(good)bye" nor "(a*)(b*)(".
| Modifier and Type | Optional Element and Description | 
|---|---|
| int | valueThe number of groups in the regular expression. |