docs: public Processor newProcessor(final String transtype) {
          if (ditaDir == null) {
              throw new IllegalStateException();
          }
          if (!Configuration.transtypes.contains(transtype)) {
              throw new IllegalArgumentException("Transtype " + transtype + " not supported");
          }
          return new Processor(ditaDir, transtype, Collections.unmodifiableMap(args));
      }