Consider a contacts list that contains the same phone number as a value stored under different name keys. For instance, the names Home, ICE Home and Ruby might all be keys for the same phone number value 07745123456. Write a method in your MapTester class called allNames that takes a single parameter of type String and returns a String result. The parameter represents a number that could be stored as a value in the phone book and the method should return a single String that is a concatentation of all the names (i.e., the keys) associated with that number. Each name in the returned String should be followed by a colon character. For instance the call: allNames(07745123456) might return Home:ICEHome:Ruby: If there are no matches for the number, return an empty string: