docs: @NullableDecl
    final String safeFormatDiff(
        @NullableDecl A actual, @NullableDecl E expected, ExceptionStore exceptions) {
      try {
        return formatDiff(actual, expected);
      } catch (RuntimeException e) {
        exceptions.addFormatDiffException(Correspondence.class, e, actual, expected);
        return null;
      }
    }