src/java.base/share/classes/java/time/Clock.java

*** 153,163 ****
       * It is equivalent to {@code system(ZoneOffset.UTC)}.
       *
       * @return a clock that uses the best available system clock in the UTC zone, not null
       */
      public static Clock systemUTC() {
!         return new SystemClock(ZoneOffset.UTC);
      }
  
      /**
       * Obtains a clock that returns the current instant using the best available
       * system clock, converting to date and time using the default time-zone.
--- 153,163 ----
       * It is equivalent to {@code system(ZoneOffset.UTC)}.
       *
       * @return a clock that uses the best available system clock in the UTC zone, not null
       */
      public static Clock systemUTC() {
!         return SystemClock.UTC;
      }
  
      /**
       * Obtains a clock that returns the current instant using the best available
       * system clock, converting to date and time using the default time-zone.
*** 196,205 ****
--- 196,208 ----
       * @param zone  the time-zone to use to convert the instant to date-time, not null
       * @return a clock that uses the best available system clock in the specified zone, not null
       */
      public static Clock system(ZoneId zone) {
          Objects.requireNonNull(zone, "zone");
+         if (zone == ZoneOffset.UTC) {
+             return SystemClock.UTC;
+         }
          return new SystemClock(zone);
      }
  
      //-------------------------------------------------------------------------
      /**
*** 449,458 ****
--- 452,463 ----
       */
      static final class SystemClock extends Clock implements Serializable {
          private static final long serialVersionUID = 6740630888130243051L;
          private static final long OFFSET_SEED =
                  System.currentTimeMillis()/1000 - 1024; // initial offest
+         static final SystemClock UTC = new SystemClock(ZoneOffset.UTC);
+ 
          private final ZoneId zone;
          // We don't actually need a volatile here.
          // We don't care if offset is set or read concurrently by multiple
          // threads - we just need a value which is 'recent enough' - in other
          // words something that has been updated at least once in the last