diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java b/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
index ae40364..b6d86e1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
@@ -37,22 +37,33 @@
 public class Properties {
   public static final Properties EMPTY_PARENT = new Properties();
 
+  protected final Properties parentProperties;
+  protected final Task origTask;
+  protected final CopyOnWrite<Task> task;
   protected Expander expander;
 
   public Properties() {
+    this(null, null);
     expander = new Expander();
   }
 
-  public Properties(ChangeData changeData, Task definition, Properties parentProperties)
-      throws OrmException {
+  public Properties(Task origTask, Properties parentProperties) {
+    this.origTask = origTask;
+    this.parentProperties = parentProperties;
+    task = new CopyOnWrite<>(origTask, t -> origTask.config.new Task(t));
+  }
+
+  public Task getTask(ChangeData changeData) throws OrmException {
     expander = new Expander();
     expander.putAll(parentProperties.expander.getAll());
-    expander.putAll(getInternalProperties(definition, changeData));
-    expander.putAll(definition.getAllProperties());
+    expander.putAll(getInternalProperties(origTask, changeData));
+    expander.putAll(origTask.getAllProperties());
 
-    definition.setExpandedProperties(expander.getAll());
-
-    expander.expandFieldValues(definition, Collections.emptySet());
+    Map<String, String> exported = expander.expand(origTask.exported);
+    if (exported != origTask.exported) {
+      task.getForWrite().exported = exported;
+    }
+    return expander.expand(task, Collections.emptySet());
   }
 
   /** Use to expand properties specifically for NamesFactories. */
@@ -63,11 +74,11 @@
         Sets.newHashSet(TaskConfig.KEY_TYPE));
   }
 
-  protected static Map<String, String> getInternalProperties(Task definition, ChangeData changeData)
+  protected static Map<String, String> getInternalProperties(Task task, ChangeData changeData)
       throws OrmException {
     Map<String, String> properties = new HashMap<>();
 
-    properties.put("_name", definition.name);
+    properties.put("_name", task.name);
 
     Change c = changeData.change();
     properties.put("_change_number", String.valueOf(c.getId().get()));
@@ -114,6 +125,26 @@
       return Collections.unmodifiableMap(valueByName);
     }
 
+    /**
+     * Expand all properties (${property_name} -> property_value) in the given text. Returns same
+     * object if no expansions occured.
+     */
+    public Map<String, String> expand(Map<String, String> map) {
+      if (map != null) {
+        boolean hasProperty = false;
+        Map<String, String> expandedMap = new HashMap<>(map.size());
+        for (Map.Entry<String, String> e : map.entrySet()) {
+          String name = e.getKey();
+          String value = e.getValue();
+          String expanded = getValueForName(name);
+          hasProperty = hasProperty || value != expanded;
+          expandedMap.put(name, expanded);
+        }
+        return hasProperty ? Collections.unmodifiableMap(expandedMap) : map;
+      }
+      return null;
+    }
+
     @Override
     public String getValueForName(String name) {
       if (!expanding.add(name)) {
@@ -157,12 +188,6 @@
     // "${_name}" -> group(1) = "_name"
     protected static final Pattern PATTERN = Pattern.compile("\\$\\{([^}]+)\\}");
 
-    /** Expand all properties in the Strings in the object's Fields (except the exclude ones) */
-    protected <T> T expandFieldValues(T object, Set<String> excludedFieldNames) {
-      // Fake the CopyOnWrite for backwards compatibility.
-      return expand(object, o -> o, excludedFieldNames);
-    }
-
     /**
      * Returns expanded object if property found in the Strings in the object's Fields (except the
      * excluded ones). Returns same object if no expansions occured.
diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java b/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java
index 97fefb7..58cb37d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java
@@ -123,14 +123,6 @@
       return all;
     }
 
-    protected void setExpandedProperties(Map<String, String> expanded) {
-      properties.clear();
-      properties.putAll(expanded);
-      for (String property : exported.keySet()) {
-        exported.put(property, properties.get(property));
-      }
-    }
-
     public String key() {
       // name is needed to differentiate Tasks from the same TasksFactory
       return super.key() + SEP + name;
diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/TaskTree.java b/src/main/java/com/googlesource/gerrit/plugins/task/TaskTree.java
index 16126af..702babb 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/TaskTree.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/TaskTree.java
@@ -155,13 +155,13 @@
     public final Task task;
     protected final Properties properties;
 
-    public Node(NodeList parent, Task definition) throws ConfigInvalidException, OrmException {
+    public Node(NodeList parent, Task task) throws ConfigInvalidException, OrmException {
       this.parent = parent;
-      this.task = definition;
+      Preloader.preload(task);
+      properties = new Properties(task, parent.getProperties());
+      this.task = properties.getTask(getChangeData());
       this.path.addAll(parent.path);
       this.path.add(key());
-      Preloader.preload(definition);
-      properties = new Properties(getChangeData(), definition, parent.getProperties());
     }
 
     public String key() {