Use PlayKeys.externalizeResources := false instead of explicitly referencing entities.

Based on this https://github.com/playframework/playframework/issues/4590#issuecomment-116888508 discussion.

frameworks/Java/play2-java/play2-java-jpa-hikaricp/build.sbt

@@ -13,4 +13,6 @@ libraryDependencies ++= Seq(
   "org.hibernate" % "hibernate-entitymanager" % "4.3.10.Final"
 )
 
-routesGenerator := InjectedRoutesGenerator
+routesGenerator := InjectedRoutesGenerator
+
+PlayKeys.externalizeResources := false

frameworks/Java/play2-java/play2-java-jpa-hikaricp/conf/META-INF/persistence.xml

@@ -6,8 +6,6 @@
     <persistence-unit name="defaultPersistenceUnit" transaction-type="RESOURCE_LOCAL">
         <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
         <non-jta-data-source>DefaultDS</non-jta-data-source>
-        <class>models.Fortune</class>
-        <class>models.World</class>
         <properties>
             <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
         </properties>