Adds profile to run Error Prone in JDK8

pom.xml

@@ -290,6 +290,27 @@
   </build>
 
   <profiles>
+    <!-- using github.com/google/error-prone-javac is required when running on JDK 8 -->
+    <profile>
+      <id>jdk8</id>
+      <activation>
+        <jdk>1.8</jdk>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+              <fork>true</fork>
+              <compilerArgs combine.children="append">
+                <arg>-J-Xbootclasspath/p:${settings.localRepository}/com/google/errorprone/javac/${maven.compiler.release}/javac-${maven.compiler.release}.jar</arg>
+              </compilerArgs>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
     <!-- Profile defining additional plugins to be executed for release -->
     <profile>
       <id>release</id>