Javac should unconditionally warn if deprecated javadoc tag is used without @Deprecated annotation

Presently, javac emits a warning under -Xlint:dep-ann mode if the @deprecated javadoc tag is used on an entity that is also not @Deprecated annotated.

JDK-8072583 requests that this warning be made unconditional. Since the "core" part of JDK-8072583 viz that javac should no longer treat @deprecated javadoc tag as requesting formal deprecation can only be undertaken in a phased manner over multiple releases of JDK, I have created the present ticket to handle the unconditional warning part of the original request - which can be implemented for JDK9.