不适用的论点？

Question

所以我有两种方法。将Set作为参数而另一个是同一事物的重载版本。出于某种原因，我打电话：

returnMap = getWordLengthMap(returnMap, itr);

它告诉我重载函数不支持参数。它基本上告诉我它不能将TreeMap或TreeSet作为Map或Set的参数？我犯了什么错误。

public static Map<Integer, Set<String>> getWordLengthMap(Set<String> theSet) {
    TreeMap<Integer, TreeSet<String>> returnMap = 
            new TreeMap<Integer, TreeSet<String>>();
    Iterator<String> itr = theSet.iterator();
    returnMap = getWordLengthMap(returnMap, itr);

}


/**
 * Description: Overloaded recursive method
 * @param theWordLengths Map containing word lengths
 * @param theWordSetItr Iterator for Strings in map
 * @return Map
 */
public static Map<Integer, Set<String>> getWordLengthMap(
        Map<Integer, Set<String>> theWordLengths,
        Iterator<String> theWordSetItr) {
    return null; //placeholder
}