Support AutoValue

AutoValue[1] is a lightweight annotation-processor-based library for
implementing classes with simple, obvious value semantics.

Add support for AutoValue to build rules and Eclipse project
generation. Buck does not currently have an officially-supported
interface for specifying annotation processor dependencies[2], so we
have to take the slightly ugly approach of monkey-patching
java_library and java_test to add annotation processor arguments to
each rule that requires annotation processing; hopefully this ugliness
can be reduced in the future.

[1] https://github.com/google/auto/tree/master/value
[2] https://github.com/facebook/buck/issues/85

Change-Id: I8b49d6f9f25d61688b667d964848c6ce106ae4ec

gerrit-common/src/test/java/com/google/gerrit/common/AutoValueTest.java

@@ -0,0 +1,39 @@
+// Copyright (C) 2014 The Android Open Source Project
+//
+// 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.gerrit.common;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.auto.value.AutoValue;
+
+import org.junit.Test;
+
+public class AutoValueTest {
+  @AutoValue
+  abstract static class Auto {
+    static Auto create(String val) {
+      return new AutoValue_AutoValueTest_Auto(val);
+    }
+
+    abstract String val();
+  }
+
+  @Test
+  public void autoValue() {
+    Auto a = Auto.create("foo");
+    assertThat(a.val()).isEqualTo("foo");
+    assertThat(a.toString()).isEqualTo("Auto{val=foo}");
+  }
+}