Check for the isEmpty() default method on the java.lang.CharSequence interface

A default isEmpty() method has been added to the java.lang.CharSequence interface in Java SE 15. Classes that implement java.lang.CharSequence and another interface which defines an isEmpty() default method might need to be modified to override the isEmpty() method.

Additionally, there is now a source incompatibility with classes that implement or interfaces that extend the java.lang.CharSequence interface and statically import an isEmpty() method. If the application is recompiled using Java SE 15, these references must be updated to use a qualified name instead of a static import.

For more information on these changes, see Added isEmpty Default Method to CharSequence.