public static @Nullable String getRelativePathFromAncestor(PsiFileSystemItem file, PsiFileSystemItem ancestor) {
    VirtualFile vFile = file != null ? file.getVirtualFile() : null;
    VirtualFile ancestorVFile = ancestor != null ? ancestor.getVirtualFile() : null;
    return vFile != null && ancestorVFile != null ? VfsUtilCore.getRelativePath(vFile, ancestorVFile, VFS_SEPARATOR_CHAR) : null;
  }
public static @Nullable String getRelativePathFromAncestor(PsiFileSystemItem file, PsiFileSystemItem ancestor)