/** @return The display string of all parameters. (NotNull) */
 @Override
 public String toString() {
   final StringBuilder sb = new StringBuilder();
   sb.append(DfTypeUtil.toClassTitle(this)).append(":");
   sb.append(xbuildColumnString());
   return sb.toString();
 }
 private String xbuildColumnString() {
   final String c = ", ";
   final StringBuilder sb = new StringBuilder();
   sb.append(c).append(_vInVarchar);
   sb.append(c).append(_vOutVarchar);
   if (sb.length() > 0) {
     sb.delete(0, c.length());
   }
   sb.insert(0, "{").append("}");
   return sb.toString();
 }