code: public void set(TemporalAdjuster adjuster) {
          Objects.requireNonNull(adjuster, "adjuster");
          synchronized (instantHolder) {
              ZonedDateTime current = ZonedDateTime.ofInstant(instantHolder.get(), zone);
              ZonedDateTime result = current.with(adjuster);
              instantHolder.set(result.toInstant());
          }
      }
docs: Adjusts this clock.
  <p>
  Atomically updates this clock to the value of the following expression:
  <pre>
  ZonedDateTime.now(thisClock)
  .with(adjuster)
  .toInstant()
  </pre>
  
  @param adjuster the adjuster to use, not null
  @throws DateTimeException if the adjustment cannot be made
  @throws ArithmeticException if numeric overflow occurs
  @see ZonedDateTime#with(TemporalAdjuster)