Given a String containing words separated by the " " (space) character, write a method wordLengths that return a Map<String, Integer> mapping each word that is contained in the String to its length. assert that the passed String is not null.

So, for example, given the String "Wow that is amazing", you would return a map with four mappings: "Wow" to 3, "that" to 4, "is" to 2, and "amazing" to 7.

Note that you should not add any import statements, since both java.util.Map and java.util.HashMap are already available.