code: public String getSigAlgOID() {
          if (sigAlgId == null)
              return null;
          ObjectIdentifier oid = sigAlgId.getOID();
          return oid.toString();
      }
docs: Gets the signature algorithm OID string from the CRL.
  An OID is represented by a set of positive whole number separated
  by ".", that means,<br>
  &lt;positive whole number&gt;.&lt;positive whole number&gt;.&lt;...&gt;
  For example, the string "1.2.840.10040.4.3" identifies the SHA-1
  with DSA signature algorithm defined in
  <a href="http://www.ietf.org/rfc/rfc3279.txt">RFC 3279: Algorithms and
  Identifiers for the Internet X.509 Public Key Infrastructure Certificate
  and CRL Profile</a>.
  
  @return the signature algorithm oid string.