Loosening the parseForeignSecurityPrincipal regex

to allow more "valid" well-known SIDs through.

src/com/google/enterprise/adaptor/ad/AdEntity.java

diff --git a/src/com/google/enterprise/adaptor/ad/AdEntity.java b/src/com/google/enterprise/adaptor/ad/AdEntity.java
index f1e60c2..a1062c9 100644
--- a/src/com/google/enterprise/adaptor/ad/AdEntity.java
+++ b/src/com/google/enterprise/adaptor/ad/AdEntity.java
@@ -308,7 +308,7 @@
     int end = dn.indexOf(',');
     String sid = dn.substring(start + 1, end);
     // check for mangled or malformed security principal format
-    if (!sid.matches("^S-1-5-21(-[0-9]+)+$")) {
+    if (!sid.matches("^S-1-[15](-[0-9]+)+$")) {
       log.fine("invalid foreign security principal [" + dn + "].");
       return null;
     }