private @Nullable BaseNameError checkBaseName(final String baseNameCandidate) {
      for (PropertiesFile propertiesFile : myPropertiesFiles) {
        final String name = propertiesFile.getVirtualFile().getName();
        if (name.startsWith(baseNameCandidate) &&
            (name.length() == baseNameCandidate.length() ||
             PropertiesUtil.BASE_NAME_BORDER_CHAR.contains(name.charAt(baseNameCandidate.length())))) {
          continue;
        }
        return new BaseNameError(name);
      }
      return null;
    }
private @Nullable BaseNameError checkBaseName(final String baseNameCandidate)