@Nullable
  private static String normalizeRelativeMap(Map<PsiFile, String> relativeMap) {
    String vector = null;
    for (String relativePath : relativeMap.values()) {
      if (vector == null) {
        vector = relativePath;
      }
      else if (vector.startsWith(relativePath + "/")) {
        vector = relativePath;
      }
      else if (!relativePath.startsWith(vector + "/") && !relativePath.equals(vector)) {
        return null;
      }
    }
    if (vector != null) {
      for (PsiFile psiFile : relativeMap.keySet()) {
        final String path = relativeMap.get(psiFile);
        relativeMap.put(psiFile, path.equals(vector) ? "" : path.substring(vector.length() + 1));
      }
    }
    return vector;
  }
@Nullable
  private static String normalizeRelativeMap(Map<PsiFile, String> relativeMap)