Intellij 13.1.3 copies JPA metamodel .java files from generated-sources into WAR's WEB-INF/classes

I have Intellij set up to generate JPA static metamodel classes.  Intellij puts the metamodel classes in $PROJECT_HOME/target/generated-sources/annotations.  When Intellij builds the application it compiles these classes and puts the class files alongside the JPA entity classes in the WAR file underneath WEB-INF/classes.  However, Intellij also copies the .java file into WEB-INF/classes.  So, for example, a JPA entity named Email, the following three files end up alonside each other in WEB-INF/classes:

Email.class
Email_.class
Email_.java

How do I make Intellij stop copying the .java file, Email_.java, into WEB-INF/classes?