code: public static String traceOutput(Map<String, Object> properties) {
      SortedSet<String> propertyNames = new TreeSet<>(properties.keySet());
      StringBuilder sb = new StringBuilder();
      sb.append("{");
      Iterator<String> propertyNameIterator = propertyNames.iterator();
      while (propertyNameIterator.hasNext()) {
        String propertyName = propertyNameIterator.next();
        sb.append(propertyName).append(": ");
        appendValue(sb, properties.get(propertyName));
        if (propertyNameIterator.hasNext()) {
          sb.append(", ");
        }
      }
      sb.append("}");
      return sb.toString();
    }
docs: Produce trace output for properties map.
  @param properties Properties
  @return Debug output