RFR (XS) CR 8014509: @Contended: explicit default value behaves differently from the implicit value

[Aleksey Shipilev]

Hi,

Please review the little parameter handling fix for @Contended:
  http://cr.openjdk.java.net/~shade/8014509/webrev.01/

Bottom-line, these guys should be equivalent:
 public class Test {
    private static class T0 {
        @Contended("") private double double1;
        @Contended("") private double double2;
    }
    private static class T1 {
        @Contended()   private double double1;
        @Contended()   private double double2;
    }
    private static class T2 {
        @Contended     private double double1;
        @Contended     private double double2;
    }
}

They are not, because we handle the default value in a weird way.

Testing:
  - 8014509 regression test on Linux x86_64/fastdebug
  - full JPRT cycle against hotspot-rt

Thanks,
Aleksey.