Switching StringBuffer to StringBuilder throughout the codebase (APIs permitting).

cas/src/main/java/org/springframework/security/cas/authentication/CasAuthenticationToken.java

@@ -121,7 +121,7 @@ public class CasAuthenticationToken extends AbstractAuthenticationToken implemen
     }
 
     public String toString() {
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         sb.append(super.toString());
         sb.append(" Assertion: ").append(this.assertion);
         sb.append(" Credentials (Service/Proxy Ticket): ").append(this.credentials);