docs: public static String convertClosureToSource(ReaderSource readerSource, ClosureExpression expression) throws Exception {
          String source = GeneralUtils.convertASTToSource(readerSource, expression);
          if (!source.startsWith("{")) {
              throw new Exception("Error converting ClosureExpression into source code. Closures must start with {. Found: " + source);
          }
          return source;
      }