Added "Until" type version. This new annotation allows you to remove members from the JSON output beginning at a certain version number.

This new annotation work in conjunction with the "@Since" annotation.

gson/src/main/java/com/google/gson/VersionExclusionStrategy.java

@@ -17,6 +17,7 @@
 package com.google.gson;
 
 import com.google.gson.annotations.Since;
+import com.google.gson.annotations.Until;
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
@@ -45,11 +46,28 @@ final class VersionExclusionStrategy implements ExclusionStrategy {
 
   private boolean isValidVersion(Annotation[] annotations) {
     for (Annotation annotation : annotations) {
-      if (annotation instanceof Since) {
-        double annotationVersion = ((Since) annotation).value();
-        if (annotationVersion > version) {
-          return false;
-        }
+      if (!isValidSince(annotation) || !isValidUntil(annotation)) {
+        return false;
+      }
+    }
+    return true;
+  }
+  
+  private boolean isValidSince(Annotation annotation) {
+    if (annotation instanceof Since) {
+      double annotationVersion = ((Since) annotation).value();
+      if (annotationVersion > version) {
+        return false;
+      }
+    }
+    return true;
+  }
+  
+  private boolean isValidUntil(Annotation annotation) {
+    if (annotation instanceof Until) {
+      double annotationVersion = ((Until) annotation).value();
+      if (annotationVersion <= version) {
+        return false;
       }
     }
     return true;

gson/src/main/java/com/google/gson/annotations/Until.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.gson.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * An annotation that indicates the version number until a member or a type should be present.
+ * Basically, if Gson is created with a version number that exceeds the value stored in the
+ * {@code Until} annotation then the field will be ignored from the JSON output.  This annotation
+ * is useful to manage versioning of your JSON classes for a web-service.
+ *
+ * <p>
+ * This annotation has no effect unless you build {@link com.google.gson.Gson} with a
+ * {@link com.google.gson.GsonBuilder} and invoke
+ * {@link com.google.gson.GsonBuilder#setVersion(double)} method.
+ *
+ * <p>Here is an example of how this annotation is meant to be used:</p>
+ * <pre>
+ * public class User {
+ *   private String firstName;
+ *   private String lastName;
+ *   &#64Until(1.1) private String emailAddress;
+ *   &#64Until(1.1) private String password;
+ * }
+ * </pre>
+ *
+ * <p>If you created Gson with {@code new Gson()}, the {@code toJson()} and {@code fromJson()}
+ * methods will use all the fields for serialization and deserialization. However, if you created
+ * Gson with {@code Gson gson = new GsonBuilder().setVersion(1.2).create()} the the
+ * {@code toJson()} and {@code fromJson()} methods of Gson will exclude the {@code emailAddress}
+ * and {@code password} fields because the version number passed to the GsonBuilder, {@code 1.2},
+ * exceeds the version number set on the {@code Until} annotation for those fields.
+ *
+ * @author Joel Leitch
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.FIELD, ElementType.TYPE})
+public @interface Until {
+
+  /**
+   * the value indicating a version number until this member
+   * or type should be ignored.
+   */
+  double value();
+}

gson/src/test/java/com/google/gson/functional/VersioningTest.java

@@ -18,6 +18,7 @@ package com.google.gson.functional;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.annotations.Since;
+import com.google.gson.annotations.Until;
 import com.google.gson.common.TestTypes.BagOfPrimitives;
 
 import junit.framework.TestCase;
@@ -42,6 +43,17 @@ public class VersioningTest extends TestCase {
     builder = new GsonBuilder();
   }
 
+  public void testVersionedUntilSerialization() {
+    Version1 target = new Version1();
+    Gson gson = builder.setVersion(1.29).create();
+    String json = gson.toJson(target);
+    assertTrue(json.contains("\"a\":" + A));
+    
+    gson = builder.setVersion(1.3).create();
+    json = gson.toJson(target);
+    assertFalse(json.contains("\"a\":" + A));
+  }
+
   public void testVersionedClassesSerialization() {
     Gson gson = builder.setVersion(1.0).create();
     String json1 = gson.toJson(new Version1());
@@ -97,7 +109,7 @@ public class VersioningTest extends TestCase {
   }
 
   private static class Version1 {
-    int a = A;
+    @Until(1.3) int a = A;
     @Since(1.0) int b = B;
   }