code: public boolean add(String key, ModuleDepInfo info) {
  		if (info == null) {
  			throw new NullPointerException();
  		}
  		boolean modified = false;
  		ModuleDepInfo existing = get(key);
  		if (!containsKey(key) || existing != info) {
  			if (existing != null) {
  				modified = existing.add(info);
  			} else {
  				super.put(key, info);
  				modified = true;
  			}
  		}
  		return modified;
  	}
docs: Adds the specified pair to the map. If an entry for the key exists, then
  the specified module dep info is added to the existing module dep info.
  
  @param key
  The module name to associate with the dep info object
  @param info
  the ModuleDepInfo object
  @return true if the map was modified