code: private java.util.Date getJavaUtilDateFromInstant(Instant instant) {
          java.util.Date javaUtilDate;
          try {
              javaUtilDate = new java.util.Date(instant.toEpochMilli());
          } catch (ArithmeticException ex) {
              throw new IllegalArgumentException(ex);
          }
          return javaUtilDate;
      }
docs: getJavaUtilDateFromInstant, Converts a "Java.time" or "backport310" instant to a
  java.util.Date. This code was copied from backport310, and should work in both java.time and
  backport310.
  
  Note: Be aware that if applying a specific time zone, then the time zone should be used to
  create the instant.