docs: @Override
      public DirectCompilerResult visitKeyString(FEEL_1_1Parser.KeyStringContext ctx) {
          // Need to repeat the same impl as visitStringLiteral because is an ANTLR terminal node, so cannot delegate.
          StringLiteralExpr expr = new StringLiteralExpr(EvalHelper.unescapeString(ParserHelper.getOriginalText(ctx)));
          return DirectCompilerResult.of(expr, BuiltInType.STRING);
      }