docs: public static final String formatTime(long timestamp, boolean useIsoDateFormat) {
          DateFormat df = dateformats.get();
          if (df == null) {
              df = getDateFormat();
              dateformats.set(df);
          }
  
          try {
              // Get and store the locale Date pattern that was retrieved from getDateTimeInstance, to be used later.
              // This is to prevent creating multiple new instances of SimpleDateFormat, which is expensive.
              String ddp = localeDatePattern.get();
              if (ddp == null) {
                  ddp = ((SimpleDateFormat) df).toPattern();
                  localeDatePattern.set(ddp);
              }
  
              if (useIsoDateFormat) {
                  ((SimpleDateFormat) df).applyPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
              } else {
                  ((SimpleDateFormat) df).applyPattern(ddp);
              }
          } catch (Exception e) {
              // Use the default pattern, instead.
          }
  
          return df.format(timestamp);
      }