diff --git a/proto/pom.xml b/proto/pom.xml
index c004fea8..d42be0f9 100644
--- a/proto/pom.xml
+++ b/proto/pom.xml
@@ -10,6 +10,9 @@
   <version>0.5</version>
   <name>Gson Protobuf Support</name>
   <description>Gson support for Protobufs</description>
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
   <distributionManagement>
     <repository>
       <id>local.repo</id>
@@ -52,21 +55,35 @@
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>
-      <version>1.7.1</version>
+      <version>2.3.1</version>
       <scope>compile</scope>
     </dependency>
 
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>2.4.0a</version>
+      <version>2.6.1</version>
+      <scope>compile</scope>
+    </dependency>
+    
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>18.0</version>
       <scope>compile</scope>
     </dependency>
 
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>3.8.2</version>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+    
+    <dependency>
+      <groupId>com.google.truth</groupId>
+      <artifactId>truth</artifactId>
+      <version>0.27</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
@@ -76,7 +93,19 @@
     <plugins>
       <plugin>
         <artifactId>maven-antrun-plugin</artifactId>
+        <version>1.8</version>
         <executions>
+        <execution>
+            <phase>blah</phase>
+            <goals>
+                <goal>run</goal>
+            </goals>
+            <configuration>
+                <target>
+                    <echoproperties />
+                </target>
+            </configuration>
+        </execution>
           <execution>
             <id>compile-protoc</id>
             <phase>generate-sources</phase>
@@ -91,6 +120,7 @@
                 <pathconvert pathsep=" " property="proto.files" refid="proto.path" />
                 <exec executable="protoc" failonerror="true">
                   <arg value="--java_out=src/main/java" />
+                  <arg value="--proto_path=/usr/include" />
                   <arg value="-I${project.basedir}/src/main/protobuf" />
                   <arg line="${proto.files}" />
                 </exec>
@@ -125,6 +155,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-install-plugin</artifactId>
+        <version>2.5.2</version>
         <!-- configuration>
           <updateReleaseInfo>true</updateReleaseInfo>
           <createChecksum>true</createChecksum>
@@ -182,7 +213,7 @@
         <artifactId>maven-assembly-plugin</artifactId>
         <configuration>
           <descriptor>src/main/resources/assembly-descriptor.xml</descriptor>
-          <finalName>proto-${version}</finalName>
+          <finalName>proto-${project.version}</finalName>
           <outputDirectory>target/dist</outputDirectory>
           <workDirectory>target/assembly/work</workDirectory>
         </configuration>
diff --git a/proto/src/main/java/com/google/gson/protobuf/ProtoTypeAdapter.java b/proto/src/main/java/com/google/gson/protobuf/ProtoTypeAdapter.java
index 7a6be05f..b5104fb1 100644
--- a/proto/src/main/java/com/google/gson/protobuf/ProtoTypeAdapter.java
+++ b/proto/src/main/java/com/google/gson/protobuf/ProtoTypeAdapter.java
@@ -16,6 +16,10 @@
 
 package com.google.gson.protobuf;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.common.base.CaseFormat;
+import com.google.common.base.Converter;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonDeserializationContext;
 import com.google.gson.JsonDeserializer;
@@ -24,25 +28,182 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonParseException;
 import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
+import com.google.protobuf.DescriptorProtos.EnumValueOptions;
+import com.google.protobuf.DescriptorProtos.FieldOptions;
 import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.EnumDescriptor;
+import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
+import com.google.protobuf.Extension;
 import com.google.protobuf.GeneratedMessage;
+import com.google.protobuf.Message;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
-import java.util.List;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 /**
- * Gson type adapter for protocol buffers
+ * GSON type adapter for protocol buffers that knows how to serialize enums either by using their
+ * values or their names, and also supports custom proto field names.
+ * <p>
+ * You can specify which case representation is used for the proto fields when writing/reading the
+ * JSON payload by calling {@link Builder#setFieldNameSerializationFormat(CaseFormat, CaseFormat)}.
+ * <p>
+ * An example of default serialization/deserialization using custom proto field names is show below:
+ *
+ * <pre>
+ * message MyMessage {
+ *   // Will be serialized as 'osBuildID' instead of the default 'osBuildId'.
+ *   string os_build_id = 1 [(serialized_name) = "osBuildID"];
+ * }
+ * </pre>
+ * <p>
  *
  * @author Inderjeet Singh
+ * @author Emmanuel Cron
+ * @author Stanley Wang
  */
-public class ProtoTypeAdapter implements JsonSerializer<GeneratedMessage>,
-    JsonDeserializer<GeneratedMessage> {
+public class ProtoTypeAdapter
+    implements JsonSerializer<GeneratedMessage>, JsonDeserializer<GeneratedMessage> {
+  /**
+   * Determines how enum <u>values</u> should be serialized.
+   */
+  public static enum EnumSerialization {
+    /**
+     * Serializes and deserializes enum values using their <b>number</b>. When this is used, custom
+     * value names set on enums are ignored.
+     */
+    NUMBER,
+    /** Serializes and deserializes enum values using their <b>name</b>. */
+    NAME;
+  }
+
+  /**
+   * Builder for {@link ProtoTypeAdapter}s.
+   */
+  public static class Builder {
+    private final Set<Extension<FieldOptions, String>> serializedNameExtensions;
+    private final Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions;
+    private EnumSerialization enumSerialization;
+    private Converter<String, String> fieldNameSerializationFormat;
+
+    private Builder(EnumSerialization enumSerialization, CaseFormat fromFieldNameFormat,
+        CaseFormat toFieldNameFormat) {
+      this.serializedNameExtensions = new HashSet<Extension<FieldOptions, String>>();
+      this.serializedEnumValueExtensions = new HashSet<Extension<EnumValueOptions, String>>();
+      setEnumSerialization(enumSerialization);
+      setFieldNameSerializationFormat(fromFieldNameFormat, toFieldNameFormat);
+    }
+
+    public Builder setEnumSerialization(EnumSerialization enumSerialization) {
+      this.enumSerialization = checkNotNull(enumSerialization);
+      return this;
+    }
+
+    /**
+     * Sets the field names serialization format. The first parameter defines how to read the format
+     * of the proto field names you are converting to JSON. The second parameter defines which
+     * format to use when serializing them.
+     * <p>
+     * For example, if you use the following parameters: {@link CaseFormat#LOWER_UNDERSCORE},
+     * {@link CaseFormat#LOWER_CAMEL}, the following conversion will occur:
+     *
+     * <pre>
+     * PROTO     <->  JSON
+     * my_field       myField
+     * foo            foo
+     * n__id_ct       nIdCt
+     * </pre>
+     */
+    public Builder setFieldNameSerializationFormat(CaseFormat fromFieldNameFormat,
+        CaseFormat toFieldNameFormat) {
+      fieldNameSerializationFormat = fromFieldNameFormat.converterTo(toFieldNameFormat);
+      return this;
+    }
+
+    /**
+     * Adds a field proto annotation that, when set, overrides the default field name
+     * serialization/deserialization. For example, if you add the ' {@code serialized_name}'
+     * annotation and you define a field in your proto like the one below:
+     *
+     * <pre>
+     * string client_app_id = 1[(serialized_name) = "appId"];
+     * </pre>
+     *
+     * ...the adapter will serialize the field using '{@code appId}' instead of the default '
+     * {@code clientAppId}'. This lets you customize the name serialization of any field of your
+     * proto.
+     */
+    public Builder addSerializedNameExtension(
+        Extension<FieldOptions, String> serializedNameExtension) {
+      serializedNameExtensions.add(checkNotNull(serializedNameExtension));
+      return this;
+    }
+
+    /**
+     * Adds an enum proto annotation that, when set, overrides the default <b>enum</b> value
+     * serialization/deerialization of this adapter. For example, if you add the '
+     * {@code serialized_value}' annotation and you define an enum in your proto like the one below:
+     *
+     * <pre>
+     * enum MyEnum {
+     *   UNKNOWN = 0;
+     *   CLIENT_APP_ID = 1 [(serialized_value) = "APP_ID"];
+     *   TWO = 2 [(serialized_value) = "2"];
+     * }
+     * </pre>
+     *
+     * ...the adapter will serialize the value {@code CLIENT_APP_ID} as "{@code APP_ID}" and the
+     * value {@code TWO} as "{@code 2}". This works for both serialization and deserialization.
+     * <p>
+     * Note that you need to set the enum serialization of this adapter to
+     * {@link EnumSerialization#NAME}, otherwise these annotations will be ignored.
+     */
+    public Builder addSerializedEnumValueExtension(
+        Extension<EnumValueOptions, String> serializedEnumValueExtension) {
+      serializedEnumValueExtensions.add(checkNotNull(serializedEnumValueExtension));
+      return this;
+    }
+
+    public ProtoTypeAdapter build() {
+      return new ProtoTypeAdapter(enumSerialization, fieldNameSerializationFormat,
+          serializedNameExtensions, serializedEnumValueExtensions);
+    }
+  }
+
+  /**
+   * Creates a new {@link ProtoTypeAdapter} builder, defaulting enum serialization to
+   * {@link EnumSerialization#NAME} and converting field serialization from
+   * {@link CaseFormat#LOWER_UNDERSCORE} to {@link CaseFormat#LOWER_CAMEL}.
+   */
+  public static Builder newBuilder() {
+    return new Builder(EnumSerialization.NAME, CaseFormat.LOWER_UNDERSCORE, CaseFormat.LOWER_CAMEL);
+  }
+
+  private static final com.google.protobuf.Descriptors.FieldDescriptor.Type ENUM_TYPE =
+      com.google.protobuf.Descriptors.FieldDescriptor.Type.ENUM;
+
+  private final EnumSerialization enumSerialization;
+  private final Converter<String, String> fieldNameSerializationFormat;
+  private final Set<Extension<FieldOptions, String>> serializedNameExtensions;
+  private final Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions;
+
+  private ProtoTypeAdapter(EnumSerialization enumSerialization,
+      Converter<String, String> fieldNameSerializationFormat,
+      Set<Extension<FieldOptions, String>> serializedNameExtensions,
+      Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions) {
+    this.enumSerialization = enumSerialization;
+    this.fieldNameSerializationFormat = fieldNameSerializationFormat;
+    this.serializedNameExtensions = serializedNameExtensions;
+    this.serializedEnumValueExtensions = serializedEnumValueExtensions;
+  }
 
   @Override
   public JsonElement serialize(GeneratedMessage src, Type typeOfSrc,
@@ -52,59 +213,91 @@ public class ProtoTypeAdapter implements JsonSerializer<GeneratedMessage>,
 
     for (Map.Entry<FieldDescriptor, Object> fieldPair : fields.entrySet()) {
       final FieldDescriptor desc = fieldPair.getKey();
-      if (desc.isRepeated()) {
-        List<?> fieldList = (List<?>) fieldPair.getValue();
-        if (fieldList.size() != 0) {
+      String name = getCustSerializedName(desc.getOptions(), desc.getName());
+
+      if (desc.getType() == ENUM_TYPE) {
+        // Enum collections are also returned as ENUM_TYPE
+        if (fieldPair.getValue() instanceof Collection) {
+          // Build the array to avoid infinite loop
           JsonArray array = new JsonArray();
-          for (Object o : fieldList) {
-            array.add(context.serialize(o));
+          @SuppressWarnings("unchecked")
+          Collection<EnumValueDescriptor> enumDescs =
+              (Collection<EnumValueDescriptor>) fieldPair.getValue();
+          for (EnumValueDescriptor enumDesc : enumDescs) {
+            array.add(context.serialize(getEnumValue(enumDesc)));
+            ret.add(name, array);
           }
-          ret.add(desc.getName(), array);
+        } else {
+          EnumValueDescriptor enumDesc = ((EnumValueDescriptor) fieldPair.getValue());
+          ret.add(name, context.serialize(getEnumValue(enumDesc)));
         }
       } else {
-        ret.add(desc.getName(), context.serialize(fieldPair.getValue()));
+        ret.add(name, context.serialize(fieldPair.getValue()));
       }
     }
     return ret;
   }
 
-  @SuppressWarnings("unchecked")
   @Override
   public GeneratedMessage deserialize(JsonElement json, Type typeOfT,
       JsonDeserializationContext context) throws JsonParseException {
     try {
       JsonObject jsonObject = json.getAsJsonObject();
-      Class<? extends GeneratedMessage> protoClass =
-        (Class<? extends GeneratedMessage>) typeOfT; 
+      @SuppressWarnings("unchecked")
+      Class<? extends GeneratedMessage> protoClass = (Class<? extends GeneratedMessage>) typeOfT;
+
       try {
         // Invoke the ProtoClass.newBuilder() method
-        Object protoBuilder = getCachedMethod(protoClass, "newBuilder")
-          .invoke(null);
-        Class<?> builderClass = protoBuilder.getClass();
+        GeneratedMessage.Builder<?> protoBuilder =
+            (GeneratedMessage.Builder<?>) getCachedMethod(protoClass, "newBuilder").invoke(null);
 
-        Descriptor protoDescriptor = (Descriptor) getCachedMethod(
-            protoClass, "getDescriptor").invoke(null);
+        Descriptor protoDescriptor =
+            (Descriptor) getCachedMethod(protoClass, "getDescriptor").invoke(null);
         // Call setters on all of the available fields
         for (FieldDescriptor fieldDescriptor : protoDescriptor.getFields()) {
-          String name = fieldDescriptor.getName();
-          if (jsonObject.has(name)) {
-            JsonElement jsonElement = jsonObject.get(name);
-            String fieldName = name + "_";
-            Field field = protoClass.getDeclaredField(fieldName);
-            Type fieldType = field.getGenericType();
-            Object fieldValue = context.deserialize(jsonElement, fieldType);
-            Method method = getCachedMethod(
-              builderClass, "setField", FieldDescriptor.class, Object.class);
-            method.invoke(protoBuilder, fieldDescriptor, fieldValue);
+          String jsonFieldName =
+              getCustSerializedName(fieldDescriptor.getOptions(), fieldDescriptor.getName());
+
+          if (jsonObject.has(jsonFieldName)) {
+            JsonElement jsonElement = jsonObject.get(jsonFieldName);
+            // Do not reuse jsonFieldName here, it might have a custom value
+            Object fieldValue;
+            if (fieldDescriptor.getType() == ENUM_TYPE) {
+              if (jsonElement.isJsonArray()) {
+                // Handling array
+                Collection<EnumValueDescriptor> enumCollection =
+                    new ArrayList<EnumValueDescriptor>();
+                for (JsonElement element : jsonElement.getAsJsonArray()) {
+                  enumCollection.add(
+                      findValueByNameAndExtension(fieldDescriptor.getEnumType(), element));
+                }
+                fieldValue = enumCollection;
+              } else {
+                // No array, just a plain value
+                fieldValue =
+                    findValueByNameAndExtension(fieldDescriptor.getEnumType(), jsonElement);
+              }
+              protoBuilder.setField(fieldDescriptor, fieldValue);
+            } else if (fieldDescriptor.isRepeated()) {
+              // If the type is an array, then we have to grab the type from the class.
+              String protoArrayFieldName =
+                  fieldNameSerializationFormat.convert(fieldDescriptor.getName()) + "_";
+              Field protoArrayField = protoClass.getDeclaredField(protoArrayFieldName);
+              Type protoArrayFieldType = protoArrayField.getGenericType();
+              fieldValue = context.deserialize(jsonElement, protoArrayFieldType);
+              protoBuilder.setField(fieldDescriptor, fieldValue);
+            } else {
+              Message prototype = protoBuilder.build();
+              Object field = prototype.getField(fieldDescriptor);
+              fieldValue = context.deserialize(jsonElement, field.getClass());
+              protoBuilder.setField(fieldDescriptor, fieldValue);
+            }
           }
         }
-        
-        // Invoke the build method to return the final proto
-        return (GeneratedMessage) getCachedMethod(builderClass, "build")
-            .invoke(protoBuilder);
+        return (GeneratedMessage) protoBuilder.build();
       } catch (SecurityException e) {
         throw new JsonParseException(e);
-      } catch (NoSuchMethodException e) {
+      } catch (NoSuchMethodException  e) {
         throw new JsonParseException(e);
       } catch (IllegalArgumentException e) {
         throw new JsonParseException(e);
@@ -114,25 +307,91 @@ public class ProtoTypeAdapter implements JsonSerializer<GeneratedMessage>,
         throw new JsonParseException(e);
       }
     } catch (Exception e) {
-      throw new JsonParseException("Error while parsing proto: ", e);
+      throw new JsonParseException("Error while parsing proto", e);
     }
   }
 
-  private static Method getCachedMethod(Class<?> clazz, String methodName,
-      Class<?>... methodParamTypes) throws NoSuchMethodException {
+  /**
+   * Retrieves the custom field name from the given options, and if not found, returns the specified
+   * default name.
+   */
+  private String getCustSerializedName(FieldOptions options, String defaultName) {
+    for (Extension<FieldOptions, String> extension : serializedNameExtensions) {
+      if (options.hasExtension(extension)) {
+        return options.getExtension(extension);
+      }
+    }
+    return fieldNameSerializationFormat.convert(defaultName);
+  }
+
+  /**
+   * Retrieves the custom enum value name from the given options, and if not found, returns the
+   * specified default value.
+   */
+  private String getCustSerializedEnumValue(EnumValueOptions options, String defaultValue) {
+    for (Extension<EnumValueOptions, String> extension : serializedEnumValueExtensions) {
+      if (options.hasExtension(extension)) {
+        return options.getExtension(extension);
+      }
+    }
+    return defaultValue;
+  }
+
+  /**
+   * Returns the enum value to use for serialization, depending on the value of
+   * {@link EnumSerialization} that was given to this adapter.
+   */
+  private Object getEnumValue(EnumValueDescriptor enumDesc) {
+    if (enumSerialization == EnumSerialization.NAME) {
+      return getCustSerializedEnumValue(enumDesc.getOptions(), enumDesc.getName());
+    } else {
+      return enumDesc.getNumber();
+    }
+  }
+
+  /**
+   * Finds an enum value in the given {@link EnumDescriptor} that matches the given JSON element,
+   * either by name if the current adapter is using {@link EnumSerialization#NAME}, otherwise by
+   * number. If matching by name, it uses the extension value if it is defined, otherwise it uses
+   * its default value.
+   *
+   * @throws IllegalArgumentException if a matching name/number was not found
+   */
+  private EnumValueDescriptor findValueByNameAndExtension(EnumDescriptor desc,
+      JsonElement jsonElement) {
+    if (enumSerialization == EnumSerialization.NAME) {
+      // With enum name
+      for (EnumValueDescriptor enumDesc : desc.getValues()) {
+        String enumValue = getCustSerializedEnumValue(enumDesc.getOptions(), enumDesc.getName());
+        if (enumValue.equals(jsonElement.getAsString())) {
+          return enumDesc;
+        }
+      }
+      throw new IllegalArgumentException(
+          String.format("Unrecognized enum name: %s", jsonElement.getAsString()));
+    } else {
+      // With enum value
+      EnumValueDescriptor fieldValue = desc.findValueByNumber(jsonElement.getAsInt());
+      if (fieldValue == null) {
+        throw new IllegalArgumentException(
+            String.format("Unrecognized enum value: %s", jsonElement.getAsInt()));
+      }
+      return fieldValue;
+    }
+  }
+
+  private static Method getCachedMethod(Class<?> clazz, String methodName)
+      throws NoSuchMethodException {
+    if (!mapOfMapOfMethods.containsKey(methodName)) {
+      mapOfMapOfMethods.put(methodName, new HashMap<Class<?>, Method>());
+    }
     Map<Class<?>, Method> mapOfMethods = mapOfMapOfMethods.get(methodName);
-    if (mapOfMethods == null) {
-      mapOfMethods = new HashMap<Class<?>, Method>();
-      mapOfMapOfMethods.put(methodName, mapOfMethods);
+    if (!mapOfMethods.containsKey(clazz)) {
+      mapOfMethods.put(clazz, clazz.getMethod(methodName));
     }
-    Method method = mapOfMethods.get(clazz);
-    if (method == null) {
-      method = clazz.getMethod(methodName, methodParamTypes);
-      mapOfMethods.put(clazz, method);
-    }
-    return method;
+    return mapOfMethods.get(clazz);
   }
 
   private static Map<String, Map<Class<?>, Method>> mapOfMapOfMethods =
-    new HashMap<String, Map<Class<?>, Method>>();
-}
\ No newline at end of file
+      new HashMap<String, Map<Class<?>, Method>>();
+}
diff --git a/proto/src/main/protobuf/annotations.proto b/proto/src/main/protobuf/annotations.proto
new file mode 100644
index 00000000..8246831f
--- /dev/null
+++ b/proto/src/main/protobuf/annotations.proto
@@ -0,0 +1,32 @@
+//
+// Copyright (C) 2010 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.
+//
+
+syntax = "proto2";
+
+package google.gson.protobuf.generated;
+option java_package = "com.google.gson.protobuf.generated";
+
+import "google/protobuf/descriptor.proto";
+
+extend google.protobuf.FieldOptions {
+  // Indicates a field name that overrides the default for serialization
+  optional string serialized_name = 92066888;
+}
+
+extend google.protobuf.EnumValueOptions {
+  // Indicates a field value that overrides the default for serialization
+  optional string serialized_value = 92066888;
+}
\ No newline at end of file
diff --git a/proto/src/main/protobuf/bag.proto b/proto/src/main/protobuf/bag.proto
index 6df147a0..26189a24 100644
--- a/proto/src/main/protobuf/bag.proto
+++ b/proto/src/main/protobuf/bag.proto
@@ -14,9 +14,11 @@
 // limitations under the License.
 //
 
-package com.google.gson.protobuf.generated;
+package google.gson.protobuf.generated;
 option java_package = "com.google.gson.protobuf.generated";
 
+import "annotations.proto";
+
 message SimpleProto {
   optional string msg = 1;
   optional int32 count = 2;
@@ -26,4 +28,38 @@ message ProtoWithRepeatedFields {
   repeated int64 numbers = 1;
   repeated SimpleProto simples = 2;
   optional string name = 3;
+}
+
+// -- A more complex message with annotations and nested protos
+
+message OuterMessage {
+  optional int32 month = 1;
+  optional int32 year = 2;
+  optional int64 long_timestamp = 3 [(serialized_name) = "timeStamp"];
+  optional string country_code_5f55 = 4;
+}
+
+message ProtoWithAnnotations {
+  optional string id = 1;
+  optional OuterMessage outer_message = 2 [(serialized_name) = "expiration_date"];
+
+  message InnerMessage {
+    optional int32 n__id_ct = 1;
+
+    enum Type {
+      UNKNOWN = 0;
+      TEXT = 1 [(serialized_value) = "text/plain"];
+      IMAGE = 2 [(serialized_value) = "image/png"];
+    }
+    optional Type content = 2;
+
+    message Data {
+      optional string data = 1;
+      optional int32 width = 2;
+      optional int32 height = 3;
+    }
+    repeated Data data = 3 [(serialized_name) = "$binary_data$"];
+  }
+  optional InnerMessage inner_message_1 = 3;
+  optional InnerMessage inner_message_2 = 4;
 }
\ No newline at end of file
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
new file mode 100644
index 00000000..e6723ac4
--- /dev/null
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2010 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.protobuf.functional;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assert_;
+
+import com.google.common.base.CaseFormat;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import com.google.gson.protobuf.ProtoTypeAdapter;
+import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
+import com.google.gson.protobuf.generated.Annotations;
+import com.google.gson.protobuf.generated.Bag.OuterMessage;
+import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations;
+import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage;
+import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Data;
+import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Type;
+import com.google.protobuf.GeneratedMessage;
+
+import junit.framework.TestCase;
+
+/**
+ * Functional tests for protocol buffers using annotations for field names and enum values.
+ *
+ * @author Emmanuel Cron
+ */
+public class ProtosWithAnnotationsTest extends TestCase {
+  private Gson gson;
+  private Gson gsonWithEnumNumbers;
+  private Gson gsonWithLowerHyphen;
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    ProtoTypeAdapter.Builder protoTypeAdapter = ProtoTypeAdapter.newBuilder()
+        .setEnumSerialization(EnumSerialization.NAME)
+        .addSerializedNameExtension(Annotations.serializedName)
+        .addSerializedEnumValueExtension(Annotations.serializedValue);
+    gson = new GsonBuilder()
+        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter.build())
+        .create();
+    gsonWithEnumNumbers = new GsonBuilder()
+        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter
+            .setEnumSerialization(EnumSerialization.NUMBER)
+            .build())
+        .create();
+    gsonWithLowerHyphen = new GsonBuilder()
+        .registerTypeHierarchyAdapter(GeneratedMessage.class, protoTypeAdapter
+            .setFieldNameSerializationFormat(CaseFormat.LOWER_UNDERSCORE, CaseFormat.LOWER_HYPHEN)
+            .build())
+        .create();
+  }
+
+  public void testProtoWithAnnotations_deserialize() {
+    String json = String.format("{  %n"
+        + "   \"id\":\"41e5e7fd6065d101b97018a465ffff01\",%n"
+        + "   \"expiration_date\":{  %n"
+        + "      \"month\":\"12\",%n"
+        + "      \"year\":\"2017\",%n"
+        + "      \"timeStamp\":\"9864653135687\",%n"
+        + "      \"countryCode5f55\":\"en_US\"%n"
+        + "   },%n"
+        // Don't define innerMessage1
+        + "   \"innerMessage2\":{  %n"
+        // Set a number as a string; it should work
+        + "      \"nIdCt\":\"98798465\",%n"
+        + "      \"content\":\"text/plain\",%n"
+        + "      \"$binary_data$\":[  %n"
+        + "         {  %n"
+        + "            \"data\":\"OFIN8e9fhwoeh8((⁹8efywoih\",%n"
+        // Don't define width
+        + "            \"height\":665%n"
+        + "         },%n"
+        + "         {  %n"
+        // Define as an int; it should work
+        + "            \"data\":65,%n"
+        + "            \"width\":-56684%n"
+        // Don't define height
+        + "         }%n"
+        + "      ]%n"
+        + "   },%n"
+        // Define a bunch of non recognizable data
+        + "   \"non_existing\":\"foobar\",%n"
+        + "   \"stillNot\":{  %n"
+        + "      \"bunch\":\"of_useless data\"%n"
+        + "   }%n"
+        + "}");
+    ProtoWithAnnotations proto = gson.fromJson(json, ProtoWithAnnotations.class);
+    assertThat(proto.getId()).isEqualTo("41e5e7fd6065d101b97018a465ffff01");
+    assertThat(proto.getOuterMessage()).isEqualTo(OuterMessage.newBuilder()
+        .setMonth(12)
+        .setYear(2017)
+        .setLongTimestamp(9864653135687L)
+        .setCountryCode5F55("en_US")
+        .build());
+    assertThat(proto.hasInnerMessage1()).isFalse();
+    assertThat(proto.getInnerMessage2()).isEqualTo(InnerMessage.newBuilder()
+        .setNIdCt(98798465)
+        .setContent(Type.TEXT)
+        .addData(Data.newBuilder()
+            .setData("OFIN8e9fhwoeh8((⁹8efywoih")
+            .setHeight(665))
+        .addData(Data.newBuilder()
+            .setData("65")
+            .setWidth(-56684))
+        .build());
+
+    String rebuilt = gson.toJson(proto);
+    assertThat(rebuilt).isEqualTo("{"
+        + "\"id\":\"41e5e7fd6065d101b97018a465ffff01\","
+        + "\"expiration_date\":{"
+        + "\"month\":12,"
+        + "\"year\":2017,"
+        + "\"timeStamp\":9864653135687,"
+        + "\"countryCode5f55\":\"en_US\""
+        + "},"
+        + "\"innerMessage2\":{"
+        + "\"nIdCt\":98798465,"
+        + "\"content\":\"text/plain\","
+        + "\"$binary_data$\":["
+        + "{"
+        + "\"data\":\"OFIN8e9fhwoeh8((⁹8efywoih\","
+        + "\"height\":665"
+        + "},"
+        + "{"
+        + "\"data\":\"65\","
+        + "\"width\":-56684"
+        + "}]}}");
+  }
+
+  public void testProtoWithAnnotations_deserializeUnknownEnumValue() {
+    String json = String.format("{  %n"
+        + "   \"content\":\"UNKNOWN\"%n"
+        + "}");
+    InnerMessage proto = gson.fromJson(json, InnerMessage.class);
+    assertThat(proto.getContent()).isEqualTo(Type.UNKNOWN);
+  }
+
+  public void testProtoWithAnnotations_deserializeUnrecognizedEnumValue() {
+    String json = String.format("{  %n"
+        + "   \"content\":\"UNRECOGNIZED\"%n"
+        + "}");
+    try {
+      gson.fromJson(json, InnerMessage.class);
+      assert_().fail("Should have thrown");
+    } catch (JsonParseException e) {
+      // expected
+    }
+  }
+
+  public void testProtoWithAnnotations_deserializeWithEnumNumbers() {
+    String json = String.format("{  %n"
+        + "   \"content\":\"0\"%n"
+        + "}");
+    InnerMessage proto = gsonWithEnumNumbers.fromJson(json, InnerMessage.class);
+    assertThat(proto.getContent()).isEqualTo(Type.UNKNOWN);
+
+    json = String.format("{  %n"
+        + "   \"content\":\"2\"%n"
+        + "}");
+    proto = gsonWithEnumNumbers.fromJson(json, InnerMessage.class);
+    assertThat(proto.getContent()).isEqualTo(Type.IMAGE);
+  }
+
+  public void testProtoWithAnnotations_serialize() {
+    ProtoWithAnnotations proto = ProtoWithAnnotations.newBuilder()
+        .setId("09f3j20839h032y0329hf30932h0nffn")
+        .setOuterMessage(OuterMessage.newBuilder()
+            .setMonth(14)
+            .setYear(6650)
+            .setLongTimestamp(468406876880768L))
+        .setInnerMessage1(InnerMessage.newBuilder()
+            .setNIdCt(12)
+            .setContent(Type.IMAGE)
+            .addData(Data.newBuilder()
+                .setData("data$$")
+                .setWidth(200))
+            .addData(Data.newBuilder()
+                .setHeight(56)))
+        .build();
+
+    String json = gsonWithLowerHyphen.toJson(proto);
+    assertThat(json).isEqualTo(
+        "{\"id\":\"09f3j20839h032y0329hf30932h0nffn\","
+        + "\"expiration_date\":{"
+            + "\"month\":14,"
+            + "\"year\":6650,"
+            + "\"timeStamp\":468406876880768"
+        + "},"
+        // This field should be using hyphens
+        + "\"inner-message-1\":{"
+            + "\"n--id-ct\":12,"
+            + "\"content\":2,"
+            + "\"$binary_data$\":["
+              + "{"
+                  + "\"data\":\"data$$\","
+                  + "\"width\":200"
+              + "},"
+              + "{"
+                  + "\"height\":56"
+              + "}]"
+            + "}"
+        + "}");
+
+    ProtoWithAnnotations rebuilt = gsonWithLowerHyphen.fromJson(json, ProtoWithAnnotations.class);
+    assertThat(rebuilt).isEqualTo(proto);
+  }
+}
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
index 7b9a1c66..964549d6 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java
@@ -18,6 +18,7 @@ package com.google.gson.protobuf.functional;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.protobuf.ProtoTypeAdapter;
+import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
 import com.google.gson.protobuf.generated.Bag.ProtoWithRepeatedFields;
 import com.google.gson.protobuf.generated.Bag.SimpleProto;
 import com.google.protobuf.GeneratedMessage;
@@ -35,8 +36,13 @@ public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    gson = new GsonBuilder().registerTypeHierarchyAdapter(
-      GeneratedMessage.class, new ProtoTypeAdapter()).create();
+    gson =
+        new GsonBuilder()
+            .registerTypeHierarchyAdapter(GeneratedMessage.class,
+                ProtoTypeAdapter.newBuilder()
+                    .setEnumSerialization(EnumSerialization.NUMBER)
+                    .build())
+            .create();
   }
 
   public void testSerializeRepeatedFields() {
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
index 55628bc5..f90899e1 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
@@ -18,6 +18,7 @@ package com.google.gson.protobuf.functional;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.protobuf.ProtoTypeAdapter;
+import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
 import com.google.gson.protobuf.generated.Bag.SimpleProto;
 import com.google.protobuf.Descriptors.Descriptor;
 import com.google.protobuf.GeneratedMessage;
@@ -31,7 +32,10 @@ public class ProtosWithPrimitiveTypesTest extends TestCase {
   protected void setUp() throws Exception {
     super.setUp();
     gson = new GsonBuilder().registerTypeHierarchyAdapter(
-      GeneratedMessage.class, new ProtoTypeAdapter()).create();
+      GeneratedMessage.class, ProtoTypeAdapter.newBuilder()
+          .setEnumSerialization(EnumSerialization.NUMBER)
+          .build())
+      .create();
   }
 
   public void testSerializeEmptyProto() {