FunctionalInterface Comparator has 2 abstract methods
equals() is not an abstract method. This method overrides Object.equals(Object), and is there only for the Comparator interface to be able to have javadoc attached to the method, explaining how comparators should implement equals(). See the javadoc of FunctionalInterface: If an interface declares an abstract method overriding one of the public methods of java.lang.Object, that … Read more