code: private void compileDefaults(Map<String, TreeMap<String, Object>> compiledDefaults, UIDefaults d) {
          for (Map.Entry<Object, Object> entry : d.entrySet()) {
  
              if (entry.getKey() instanceof String) {
                  String key = (String) entry.getKey();
                  String kp  = parsePrefix(key);
  
                  if (kp == null)
                      continue;
  
                  TreeMap<String, Object> map = compiledDefaults.get(kp);
  
                  if (map == null) {
                      map = new TreeMap<String, Object>();
                      compiledDefaults.put(kp, map);
                  }
  
                  map.put(key, entry.getValue());
              }
          }
      }
docs: Iterates over all the keys in the specified UIDefaults and compiles those
  keys into the comiledDefaults data structure. It relies on parsing the
  "prefix" out of the key. If the key is not a String or is null then it is
  ignored. In all other cases a prefix is parsed out (even if that prefix
  is the empty String or is a "fake" prefix. That is, suppose you had a key
  Foo~~MySpecial.KeyThing~~. In this case this is not a SeaGlass formatted
  key, but we don't care, we treat it as if it is. This doesn't pose any
  harm, it will simply never be used).
  
  @param compiledDefaults the compiled defaults data structure.
  @param d                the UIDefaults to be parsed.