code: private Map<String, TypeName> convertPropertiesToTypes(Map<String, ExecutableElement> properties) {
      Map<String, TypeName> types = new LinkedHashMap<>();
      for (Map.Entry<String, ExecutableElement> entry : properties.entrySet()) {
        ExecutableElement el = entry.getValue();
        types.put(entry.getKey(), TypeName.get(el.getReturnType()));
      }
      return types;
    }
docs: Converts the ExecutableElement properties to TypeName properties