code: public Long getDeprecatedMillis() {
      try {
        return deprecated != null
            ? TIMESTAMP_FORMATTER.parse(deprecated, Instant.FROM).toEpochMilli()
            : null;
      } catch (DateTimeParseException ex) {
        throw new IllegalStateException(ex.getMessage(), ex);
      }
    }
docs: Returns the timestamp (in milliseconds since epoch) on or after which the deprecation state of
  this resource will be changed to {@link Status#DEPRECATED}. Returns {@code null} if not set.
  
  @throws IllegalStateException if {@link #getDeprecated()} is not a valid date, time or datetime