code: public static DnsTextEndpointGroup of(String hostname, Function<byte[], Endpoint> mapping) {
          return new DnsTextEndpointGroupBuilder(hostname, mapping).build();
      }
docs: Creates a {@link DnsTextEndpointGroup} that schedules queries on a random {@link EventLoop} from
  {@link CommonPools#workerGroup()}.
  
  @param hostname the hostname to query DNS queries for
  @param mapping the {@link Function} that maps the content of a {@code TXT} record into
  an {@link Endpoint}. The {@link Function} is expected to return {@code null}
  if the record contains unsupported content.