code: public Principal getIssuerDN() {
          if (info == null)
              return null;
          try {
              Principal issuer = (Principal)info.get(X509CertInfo.ISSUER + DOT +
                                                     X509CertInfo.DN_NAME);
              return issuer;
          } catch (Exception e) {
              return null;
          }
      }
docs: Gets the issuer distinguished name from the certificate.
  
  @return the issuer name.