code: public void set(String name, String namespace, Object value) {
          if (value != null) {
              if (value instanceof Date) {
                  attributes.put(new XAttributeName(name, namespace, null), formatDateTime((Date)value));
              } else {
                  attributes.put(new XAttributeName(name, namespace, null), value.toString());
              }
          } else {
              attributes.remove(new XAttributeName(name, namespace, null));
          }
      }
docs: Set an attribute value identified by a local name and namespace.
  @param name the attribute name
  @param namespace the attribute namespace
  @param value the value, if null, the attribute will be removed