code: public DerValue[] getSet(int startLen) throws IOException {
          tag = (byte)buffer.read();
          if (tag != DerValue.tag_Set)
              throw new IOException("Set tag error");
          return readVector(startLen);
      }
docs: Return a set of encoded entities.  ASN.1 sets are unordered,
  though DER may specify an order for some kinds of sets (such
  as the attributes in an X.500 relative distinguished name)
  to facilitate binary comparisons of encoded values.
  
  @param startLen guess about how large the set will be
  (used to initialize an auto-growing data structure)
  @return array of the values in the sequence