code: public void set(String name, Object obj) throws IOException {
          if (!(obj instanceof X500Name)) {
              throw new IOException("Attribute must be of type X500Name.");
          }
          if (name.equalsIgnoreCase(DN_NAME)) {
              this.dnName = (X500Name)obj;
              this.dnPrincipal = null;
          } else {
              throw new IOException("Attribute name not recognized by " +
                                    "CertAttrSet:CertificateIssuerName.");
          }
      }
docs: Set the attribute value.