Enable Google error-prone

pom.xml

@@ -96,6 +96,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.3</version>
         <configuration>
+          <compilerId>javac-with-errorprone</compilerId>
+          <forceJavacCompilerUse>true</forceJavacCompilerUse>
           <source>1.7</source>
           <target>1.7</target>
           <showDeprecation>true</showDeprecation>
@@ -104,6 +106,13 @@
             <Xlint />
           </compilerArguments>
         </configuration>
+        <dependencies>
+          <dependency>
+            <groupId>org.codehaus.plexus</groupId>
+            <artifactId>plexus-compiler-javac-errorprone</artifactId>
+            <version>2.5</version>
+          </dependency>
+        </dependencies>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>