When there is an obvious implementation of an interface method in terms of other interface methods, consider providing implementation assistance to programmers in the form of a default method. For an example of this technique, see the removeIf method on page 104. If you provide default methods, be sure to document them for inheritance using the @implSpec Javadoc tag (Item 19).
How different really is interfaces with default implementations from multiple inheritance though? No state I guess, that’s a good point.
It's pretty typical to do this in Android; …