Release Note: Added isEmpty Default Method to CharSequence

`java.lang.CharSequence` has been updated in this release to define a default `isEmpty` method that tests if a character sequence is empty. Testing for, and filtering out, empty `String`s and other `CharSequence`s is a common occurrence in code and `CharSequence::isEmpty` can be used as a method reference. Classes that implement `java.lang.CharSequence` and another interface that defines `isEmpty` method should be aware of this addition as they may need to be modified to override the `isEmpty` method.