Java backend fails to escape `\n` inside terminator/separator

[katrinafyi]

This leads to a syntax error inside PrettyPrinter.java.

rules Entry ::= [A];
rules A ::= "a";
separator A "\n";

~/Downloads/bnfc-2.9.6.3-linux.binary a.cf -java           

Generated code with the un-escaped newline in render().

  private static void ppListA(java.util.Iterator<a.Absyn.A> it, int _i_)
  {
    if (it.hasNext())
    { /* cons */
      a.Absyn.A el = it.next();
      pp(el, _i_); render("
"); ppListA(it, _i_);
    }
  }

Of course, because of whitespace normalisation, a "\n" separator is the same as a " " separator and we could just use that instead. But it would be nice to avoid the syntax error.

I haven't tested all other backends. The Ocaml and Tree-sitter ones seemed to be fine with the same grammar.