code: private void validateRequiredProps(LocalComponent localComponent,
        Set<LocalComponentProp> foundProps) {
      String missingRequiredProps = localComponent
          .getRequiredProps()
          .stream()
          .filter(prop -> !foundProps.contains(prop))
          .map(prop -> "\"" + propNameToAttributeName(prop.getPropName()) + "\"")
          .collect(Collectors.joining(","));
  
      if (!missingRequiredProps.isEmpty()) {
        logger.error("Missing required property: "
            + missingRequiredProps
            + " on child component \""
            + localComponent.getComponentTagName()
            + "\"");
      }
    }
docs: Validate that all the required properties of a local components are present on a the HTML
  {@link Element} that represents it.
  
  @param localComponent The {@link LocalComponent} we want to check
  @param foundProps The props we found on the HTML {@link Element} during processing