docs: private C doRegister(Object provider, int bindingPriority, Class<?>... contracts) {
          if (contracts == null || contracts.length == 0) {
              LOG.warning("Null, empty or invalid contracts specified for " + provider + "; ignoring.");
              return configurable;
          }
          return doRegister(provider, ConfigurationImpl.initContractsMap(bindingPriority, contracts));
      }