@Contract("null -> null")
  @Nullable
  public static PropertiesFile getPropertiesFile(@Nullable PsiFile file) {
    if (!canBePropertyFile(file)) return null;
    return file instanceof PropertiesFile ? (PropertiesFile)file : XmlPropertiesFileImpl.getPropertiesFile(file);
  }
@Contract("null -> null")
  @Nullable
  public static PropertiesFile getPropertiesFile(@Nullable PsiFile file)