The Applet API has been deprecated for removal

The following Applet API classes and interfaces were deprecated for removal in Java SE 17:
java.applet.Applet
java.applet.AppletStub
java.applet.AppletContext
java.applet.AudioClip
javax.swing.JApplet
java.beans.AppletInitializer

Any API elements that reference the above and classes and interfaces are also deprecated for removal. This includes methods and fields in:
java.beans.Beans
javax.swing.RepaintManager
javax.naming.Context

For more information on the deprecation of this API, see Deprecate the Applet API for Removal.