docs: public java.util.TimeZone toTimeZone() {
          String id = getID();
          if (id.length() == 6 && (id.startsWith("+") || id.startsWith("-"))) {
              // standard format offset [+-]hh:mm
              // our ID is without any prefix, so we need to add the GMT back
              return java.util.TimeZone.getTimeZone("GMT" + getID());
          }
          // unusual offset, so setup a SimpleTimeZone as best we can
          return new java.util.SimpleTimeZone(iWallOffset, getID());
      }