fix minor typo in comment

Author: plummercj

src/jdk.jdi/share/classes/com/sun/tools/jdi/EventSetImpl.java

@@ -669,7 +669,7 @@ synchronized void build() {
                 try {
                     vm.printTrace("Event: " + evt);
                 } catch (VMDisconnectedException ee) {
-                    // Ignore. See bug 6502716
+                    // Ignore. See bug 6502716.
                 } catch (ObjectCollectedException oce) {
                     // Ignore. See bug 8373102. Can happen with SUSPEND_NONE events.
                     vm.printTrace("Event: <got ObjectCollectedException>");