docs: protected static String toPackageName(String rootPackage,  File packageName) {
  		final StringBuilder name = new StringBuilder();
  		File tmp = packageName;
  		while (tmp != null) {
  			final String elementName = tmp.getName();
  			if (!Strings.equal(FileSystem.CURRENT_DIRECTORY, elementName)
  					&& !Strings.equal(FileSystem.PARENT_DIRECTORY, elementName)) {
  				if (name.length() > 0) {
  					name.insert(0, "."); //$NON-NLS-1$
  				}
  				name.insert(0, elementName);
  			}
  			tmp = tmp.getParentFile();
  		}
  		if (!Strings.isEmpty(rootPackage)) {
  			if (name.length() > 0) {
  				name.insert(0, "."); //$NON-NLS-1$
  			}
  			name.insert(0, rootPackage);
  		}
  		return name.toString();
  	}