Class names with $ generates a warning

When a class name with $ is loaded, a warning was logged

WARN [org.jboss.as.server.deployment] (MSC service thread 1-15) JBAS015893:
Encountered invalid class name
'com.sun.jersey.json.impl.provider.entity.JSONRootElementProvider$App' for service
type 'javax.ws.rs.ext.MessageBodyReader'

But as http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.8, the $ is a valid character:

The "Java letters" include uppercase and lowercase ASCII Latin letters A-Z (\u0041-\u005a), and a-z (\u0061-\u007a), and, for historical reasons, the ASCII underscore (_, or \u005f) and dollar sign ($, or \u0024).
The $ character should be used only in mechanically generated source code or, rarely, to access pre-existing names on legacy systems.

More info about this warning: https://access.redhat.com/solutions/263373