Return a hierarchy of a given string separated by "."

classHierarchy.md

public class KV {
  String key;
  String value;
}

/* Input:
      [
        new KV("foo.bar.baz", "james"),
        new KV("foo.blah", "Terry"),
        new KV("foo.bar.meow.height", "15"),
        new KV("foo.meow.size", "11")
      ]
      
    Output:
        foo: {
           bar: {
             baz: "james"
             meow: {
                height: 15
             }
           },
           blah: "Terry",
           meow: {
              size: 11
           }
        }
      
*/
public HashMap<String, ? extends Object> geHierarchy(KV[] dataset) {
 

}