Add SubnodeList.markAsChanged() method, fix SubnodeList class javadoc.

src/helma/objectmodel/db/Node.java

@@ -365,7 +365,7 @@ public final class Node implements INode, Serializable {
      */
     public void markSubnodesChanged() {
         if (subnodes != null) {
-            subnodes.lastSubnodeChange += 1;
+            subnodes.markAsChanged();
         }
     }
 

src/helma/objectmodel/db/SubnodeList.java

@@ -21,7 +21,7 @@ import java.util.List;
 import java.io.Serializable;
 
 /**
- * A subclass of ArrayList that adds an addSorted(Object) method to
+ * Container implementation for subnode collections.
  */
 public class SubnodeList implements Serializable {
 
@@ -169,6 +169,10 @@ public class SubnodeList implements Serializable {
                 checkSum : checkSum + rel.otherType.getLastDataChange();
     }
 
+    protected synchronized void markAsChanged() {
+        lastSubnodeChange += 1;
+    }
+
     protected boolean hasRelationalNodes() {
         DbMapping dbmap = getSubnodeMapping();
         return (dbmap != null && dbmap.isRelational()