code: public LoggingFraction customHandler(String name, String module, String className, Properties properties, String formatter) {
          Map<Object, Object> handlerProperties = new HashMap<>();
          final Enumeration<?> names = properties.propertyNames();
          while (names.hasMoreElements()) {
              final String nextElement = (String) names.nextElement();
              handlerProperties.put(nextElement, properties.getProperty(nextElement));
          }
  
          customHandler(new CustomHandler(name)
                  .module(module)
                  .attributeClass(className)
                  .formatter(formatter)
                  .properties(handlerProperties));
          return this;
      }
docs: Add a CustomHandler to this logger
  
  @param name       the name of the handler
  @param module     the module that the handler uses
  @param className  the handler class name
  @param properties properties for the handler
  @param formatter  a pattern string for the formatter
  @return this fraction