docs: public static DERGeneralizedTime getInstance(
          Object  obj)
      {
          if (obj == null || obj instanceof DERGeneralizedTime)
          {
              return (DERGeneralizedTime)obj;
          }
  
          if (obj instanceof ASN1OctetString)
          {
              return new DERGeneralizedTime(((ASN1OctetString)obj).getOctets());
          }
  
          throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
      }