doc-files HTML pages are part of the docs bundle and linked from javadoc. The copyright footer in API specification are added by javadoc tool and have no effect to these doc-files pages. The doc-files HTML files may have the copyright in the comment that is not shown when browsing the docs bundle.

Some has a header and footer:
  http://download.java.net/java/jdk9/docs/api/javafx/fxml/doc-files/introduction_to_fxml.html

Some don't:
http://download.java.net/java/jdk9/docs/api/java/lang/doc-files/threadPrimitiveDeprecation.html
http://download.java.net/java/jdk9/docs/api/java/awt/doc-files/FocusSpec.html

The minimum would be to add a copyright footer in the doc-files page.