code: public boolean isLogger(String loggerName) throws Exception {
          Address addr = Address.root().add(SUBSYSTEM, LOGGING, LOGGER, loggerName);
          return null != readResource(addr);
      }
docs: Checks to see if there is already a logger with the given name.
  
  @param loggerName the name to check (this is also known as the category name)
  @return true if there is a logger/category with the given name already in existence
  @throws Exception any error