code: public void setDateTimeZone(Object dtz) throws JspTagException {
          if (dtz == null || dtz instanceof String
                  && ((String) dtz).length() == 0) {
              this.dateTimeZone = null;
          } else if (dtz instanceof DateTimeZone) {
              this.dateTimeZone = (DateTimeZone) dtz;
          } else {
              try {
                  this.dateTimeZone = DateTimeZone.forID((String) dtz);
              } catch (IllegalArgumentException iae) {
                  this.dateTimeZone = DateTimeZone.UTC;
              }
          }
      }
docs: Sets the zone attribute.
  
  @param dtz  the zone