docs: private static JoseFactory loadSpi(ClassLoader cl) {
          if (cl == null) {
              return null;
          }
  
          // start from the root CL and go back down to the TCCL
          JoseFactory instance = loadSpi(cl.getParent());
  
          if (instance == null) {
              ServiceLoader<JoseFactory> sl = ServiceLoader.load(JoseFactory.class, cl);
              URL u = cl.getResource("/META-INF/services/org.wildfly.swarm.jose.provider.JoseFactory");
              log.debugf("loadSpi, cl=%s, u=%s, sl=%s", cl, u, sl);
              try {
                  for (Object spi : sl) {
                      if (spi instanceof JoseFactory) {
                          if (instance != null) {
                              log.warn("Multiple JoseFactory implementations found: "
                                  + spi.getClass().getName() + " and " + instance.getClass().getName());
                              break;
                          } else {
                              log.debugf("sl=%s, loaded=%s", sl, spi);
                              instance = (JoseFactory)spi;
                          }
                      }
                  }
              } catch (Throwable e) {
                  log.warn("Failed to locate JoseFactory provider", e);
              }
          }
          return instance;
      }