docs: public void write(LicenseKeyPair pair, IOFormat format) throws IOException {
          switch (format) {
              case BINARY:
                  osPrivate.write(pair.getPrivate());
                  osPublic.write(pair.getPublic());
                  return;
              case BASE64:
                  osPrivate.write(Base64.getEncoder().encode(pair.getPrivate()));
                  osPublic.write(Base64.getEncoder().encode(pair.getPublic()));
                  return;
          }
          throw new IllegalArgumentException("Key format " + format + " is unknown.");
      }