Counterpart to https://vanadium-review.googlesource.com/16648

MultiPart: 6/7
Change-Id: I82165424caf8449bcedb1cc94c915f3652de69f8
diff --git a/src/main/java/io/v/baku/sample/travel/TravelService.java b/src/main/java/io/v/baku/sample/travel/TravelService.java
index 097247e..dd3f106 100644
--- a/src/main/java/io/v/baku/sample/travel/TravelService.java
+++ b/src/main/java/io/v/baku/sample/travel/TravelService.java
@@ -21,6 +21,7 @@
 import io.v.v23.security.Blessings;
 import io.v.v23.security.VCertificate;
 import io.v.v23.security.VPrincipal;
+import io.v.v23.security.VSecurity;
 import io.v.v23.verror.VException;
 import io.v.v23.vom.VomUtil;
 
@@ -91,7 +92,7 @@
         principal.blessingStore().set(blessings, new BlessingPattern("..."));
 
         // Trust these blessings and all the "parent" blessings.
-        principal.addToRoots(blessings);
+        VSecurity.addToRoots(principal, blessings);
 
         // Our security environment is now set-up. Let's find a home in the
         // namespace for our service.