diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/Copier.java b/src/main/java/com/googlesource/gerrit/plugins/task/Copier.java
index 2c0ccad..10f4048 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/Copier.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/Copier.java
@@ -14,44 +14,19 @@
 
 package com.googlesource.gerrit.plugins.task;
 
-import com.google.common.primitives.Primitives;
 import java.lang.reflect.Field;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
 
 public class Copier {
-  protected static <T> void deepCopyDeclaredFields(
-      Class<T> cls,
-      T from,
-      T to,
-      boolean includeInaccessible,
-      Collection<Class<?>> copyReferenceOnly) {
+  protected static <T> void shallowCopyDeclaredFields(
+      Class<T> cls, T from, T to, boolean includeInaccessible) {
     for (Field field : cls.getDeclaredFields()) {
       try {
         if (includeInaccessible) {
           field.setAccessible(true);
         }
-        Class<?> fieldCls = field.getType();
         Object val = field.get(from);
-        if (field.getType().isPrimitive()
-            || Primitives.isWrapperType(fieldCls)
-            || (val instanceof String)
-            || val == null
-            || copyReferenceOnly.contains(fieldCls)) {
+        if (!field.getName().equals("this$0")) { // Can't copy internal final field
           field.set(to, val);
-        } else if (val instanceof List) {
-          List<?> list = List.class.cast(val);
-          field.set(to, new ArrayList<>(list));
-        } else if (val instanceof Map) {
-          Map<?, ?> map = Map.class.cast(val);
-          field.set(to, new HashMap<>(map));
-        } else if (field.getName().equals("this$0")) { // Can't copy internal final field
-        } else {
-          throw new RuntimeException(
-              "Don't know how to deep copy " + fieldValueToString(field, val));
         }
       } catch (IllegalAccessException e) {
         if (includeInaccessible) {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/CopyOnWrite.java b/src/main/java/com/googlesource/gerrit/plugins/task/CopyOnWrite.java
index efafd57..8369d67 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/CopyOnWrite.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/CopyOnWrite.java
@@ -14,9 +14,58 @@
 
 package com.googlesource.gerrit.plugins.task;
 
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Optional;
 import java.util.function.Function;
 
 public class CopyOnWrite<T> {
+  public static class CloneOnWrite<C extends Cloneable> extends CopyOnWrite<C> {
+    public CloneOnWrite(C cloneable) {
+      super(cloneable, copier(cloneable));
+    }
+  }
+
+  public static <C extends Cloneable> Function<C, C> copier(C cloneable) {
+    return c -> clone(c);
+  }
+
+  @SuppressWarnings("unchecked")
+  public static <C extends Cloneable> C clone(C cloneable) {
+    try {
+      for (Class<?> cls = cloneable.getClass(); cls != null; cls = cls.getSuperclass()) {
+        Optional<Method> optional = getOptionalDeclaredMethod(cls, "clone");
+        if (optional.isPresent()) {
+          Method clone = optional.get();
+          clone.setAccessible(true);
+          return (C) cloneable.getClass().cast(clone.invoke(cloneable));
+        }
+      }
+      throw new RuntimeException("Cannot find clone() method");
+    } catch (SecurityException
+        | IllegalAccessException
+        | IllegalArgumentException
+        | InvocationTargetException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  /**
+   * A faster getDeclaredMethod() without exceptions. The original apparently does a linear search
+   * anyway, and it is significantly slower when it throws NoSuchMethodExceptions.
+   */
+  public static Optional<Method> getOptionalDeclaredMethod(
+      Class<?> cls, String name, Class<?>... parameterTypes) {
+    for (Method method : cls.getDeclaredMethods()) {
+      if (method.getName().equals(name)
+          && Arrays.equals(method.getParameterTypes(), parameterTypes)) {
+        return Optional.of(method);
+      }
+    }
+    return Optional.empty();
+  }
+
   protected Function<T, T> copier;
   protected T original;
   protected T copy;
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 4a04e2e..952b9a3 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
@@ -60,7 +60,7 @@
   public Properties(TaskTree.Node node, Task origTask) {
     this.node = node;
     this.origTask = origTask;
-    task = new CopyOnWrite<>(origTask, t -> origTask.config.new Task(t));
+    task = new CopyOnWrite.CloneOnWrite<>(origTask);
   }
 
   /** Use to expand properties specifically for Tasks. */
@@ -103,10 +103,7 @@
 
   /** Use to expand properties specifically for NamesFactories. */
   public NamesFactory getNamesFactory(NamesFactory namesFactory) {
-    return expander.expand(
-        namesFactory,
-        nf -> namesFactory.config.new NamesFactory(nf),
-        ImmutableSet.of(TaskConfig.KEY_TYPE));
+    return expander.expand(namesFactory, ImmutableSet.of(TaskConfig.KEY_TYPE));
   }
 
   protected Function<String, String> getParentMapper() {
@@ -281,6 +278,14 @@
      * Returns expanded object if property found in the Strings in the object's Fields (except the
      * excluded ones). Returns same object if no expansions occurred.
      */
+    public <C extends Cloneable> C expand(C object, Set<String> excludedFieldNames) {
+      return expand(new CopyOnWrite.CloneOnWrite<>(object), 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 occurred.
+     */
     public <T> T expand(T object, Function<T, T> copier, Set<String> excludedFieldNames) {
       return expand(new CopyOnWrite<>(object, copier), excludedFieldNames);
     }
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 9236db7..b4e79e0 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfig.java
@@ -14,13 +14,11 @@
 
 package com.googlesource.gerrit.plugins.task;
 
-import com.google.common.collect.Sets;
 import com.google.gerrit.common.Container;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.server.git.meta.AbstractVersionedMetaData;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -94,7 +92,7 @@
 
     protected TaskBase(TaskBase base) {
       this(base.subSection);
-      Copier.deepCopyDeclaredFields(TaskBase.class, base, this, false, copyOnlyReferencesFor());
+      Copier.shallowCopyDeclaredFields(TaskBase.class, base, this, false);
     }
 
     protected TaskBase(SubSectionKey s) {
@@ -102,7 +100,7 @@
     }
   }
 
-  public class Task extends TaskBase {
+  public class Task extends TaskBase implements Cloneable {
     public final TaskKey key;
 
     public Task(SubSectionKey s, boolean isVisible, boolean isMasqueraded) {
@@ -110,14 +108,6 @@
       key = TaskKey.create(s);
     }
 
-    public Task(Task task) {
-      super(task);
-      // Despite being copied in Copier.deepCopyDeclaredFields this
-      // is needed to avoid the final variable initialization warning.
-      this.key = task.key;
-      Copier.deepCopyDeclaredFields(Task.class, task, this, false, copyOnlyReferencesFor());
-    }
-
     public Task(TasksFactory tasks, String name) {
       super(tasks);
       key = TaskKey.create(tasks.subSection, name);
@@ -156,7 +146,7 @@
     }
   }
 
-  public class NamesFactory extends SubSection {
+  public class NamesFactory extends SubSection implements Cloneable {
     public String changes;
     public List<String> names;
     public String type;
@@ -167,11 +157,6 @@
       names = getStringList(s, KEY_NAME);
       type = getString(s, KEY_TYPE, null);
     }
-
-    public NamesFactory(NamesFactory n) {
-      super(n.subSection);
-      Copier.deepCopyDeclaredFields(NamesFactory.class, n, this, false, copyOnlyReferencesFor());
-    }
   }
 
   public class External extends SubSection {
@@ -287,7 +272,7 @@
     for (String name : names) {
       valueByName.put(name, getString(s, name));
     }
-    return valueByName;
+    return Collections.unmodifiableMap(valueByName);
   }
 
   protected Set<String> getMatchingNames(SubSectionKey s, String match) {
@@ -297,7 +282,7 @@
         matched.add(name);
       }
     }
-    return matched;
+    return Collections.unmodifiableSet(matched);
   }
 
   protected Set<String> getNames(SubSectionKey s) {
@@ -321,8 +306,4 @@
   protected SubSectionKey subSectionKey(String section, String subSection) {
     return SubSectionKey.create(file, section, subSection);
   }
-
-  protected Collection<Class<?>> copyOnlyReferencesFor() {
-    return Sets.newHashSet(TaskKey.class, SubSectionKey.class);
-  }
 }