bug5239: factored the "!" into a DENY_PREFIX constant and used consistently

java/com.sap.sse.security.common/src/com/sap/sse/security/shared/SecurityAccessControlList.java

@@ -32,6 +32,8 @@ import com.sap.sse.security.shared.impl.UserGroupImpl;
  *
  */
 public interface SecurityAccessControlList<G extends SecurityUserGroup<?>> extends Serializable {
+    String DENY_PREFIX = "!";
+
     /**
      * Checks whether this access control list grants the {@code user} the permission to execute {@code action} on the
      * object to which this ACL pertains.
@@ -80,7 +82,20 @@ public interface SecurityAccessControlList<G extends SecurityUserGroup<?>> exten
      * @return {@code true} if it is a denied action, {@code false} otherwise
      */
     static boolean isDeniedAction(String action) {
-        return action.startsWith("!");
+        return action.startsWith(DENY_PREFIX);
+    }
+
+    /**
+     * Removes a leading ! (see {@link #DENY_PREFIX}) if there is one; otherwise prefixes the action with a !
+     */
+    static String invertAction(String action) {
+        final String result;
+        if (isDeniedAction(action)) {
+            result = action.substring(DENY_PREFIX.length());
+        } else {
+            result = DENY_PREFIX+action;
+        }
+        return result;
     }
 
 }

java/com.sap.sse.security.common/src/com/sap/sse/security/shared/impl/AbstractAccessControlList.java

@@ -106,7 +106,7 @@ public abstract class AbstractAccessControlList<G extends SecurityUserGroup<?>>
         }
         for (final Entry<G, Set<WildcardPermission>> allowedEntry : deniedActionsByUserGroup.entrySet()) {
             for (final WildcardPermission permission : allowedEntry.getValue()) {
-                Util.addToValueSet(result, allowedEntry.getKey(), "!"+permission.toString());
+                Util.addToValueSet(result, allowedEntry.getKey(), invertAction(permission.toString()));
             }
         }
         return result;
@@ -120,13 +120,7 @@ public abstract class AbstractAccessControlList<G extends SecurityUserGroup<?>>
      * Removes a leading ! if there is one; otherwise prefixes the action with a !
      */
     private String invertAction(String action) {
-        final String result;
-        if (isDeniedAction(action)) {
-            result = action.substring(1);
-        } else {
-            result = "!"+action;
-        }
-        return result;
+        return SecurityAccessControlList.invertAction(action);
     }
     
     private boolean denyPermission(G userGroup, String action) {