code: @Override
     public void writeClassBody(Definition def, Writer out) throws IOException
     {
        int indent = 1;
        out.write("public interface " + getClassName(def));
        writeLeftCurlyBracket(out, 0);
        writeWithIndent(out, indent, "/**\n");
        writeWithIndent(out, indent, " * Receive message\n");
        writeWithIndent(out, indent, " * @param msg String.\n");
        writeWithIndent(out, indent, " */\n");
  
        writeWithIndent(out, indent, "public void onMessage(String msg);");
  
        writeRightCurlyBracket(out, 0);
     }
docs: Output class
  
  @param def definition
  @param out Writer
  @throws IOException ioException