docs: public static final PackageBuilder findPackageBuilder(String name)
      {
          Objects.requireNonNull(name, "name cannot be null");
          ServiceLoader<PackageBuilderProvider> loader = ServiceLoader.load(PackageBuilderProvider.class);
          Iterator<PackageBuilderProvider> iterator = loader.iterator();
          while (iterator.hasNext())
          {
              PackageBuilderProvider pbp = iterator.next();
              if (name.equals(pbp.getPackageBuilderName()))
              {
                  Mapper.setKey(name);
                  return pbp.newInstance();
              }
          }
          throw new UnsupportedOperationException("package builder "+name+" not found");
      }