--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.chromium.sdk/src/org/chromium/sdk/internal/protocolparser/JsonSubtypeCondition.java	Wed Dec 23 17:13:18 2009 -0800
@@ -0,0 +1,29 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.sdk.internal.protocolparser;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Specifies a condition for a field-reading method. It is one from group of annotations
+ * that mark key fields for choosing particular subtype. They set conditions on JSON fields in
+ * a subtype interface that drive subtype auto-selection at parsing time.
+ * <p>
+ * Specifies a general condition; it requires that:
+ * <ul>
+ * <li>field should be null, if {@link #valueIsNull()} is true,
+ * <li>field should be absent, if {@link #fieldIsAbsent()} is true,
+ * <li>field should exist, if no options are set.
+ * </ul>
+ */
+@Target({ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface JsonSubtypeCondition {
+  boolean fieldIsAbsent() default false;
+  boolean valueIsNull() default false;
+}