Obtains a clock that returns the current _instant using the best available
system clock, converting to date and time using the UTC time-zone.
!(p)
This clock, rather than {@link #systemDefaultZone()}, should be used when
you need the current _instant without the date or time.
!(p)
This clock is based on the best available system clock.
This may use {@link System#currentTimeMillis()}, or a higher resolution
clock if one is available.
!(p)
Conversion from _instant to date or time uses the {@linkplain ZoneOffset#UTC UTC time-zone}.
!(p)
The returned implementation is immutable, thread-safe and {@code Serializable}.
It is equivalent to {@code system(ZoneOffset.UTC)}.
@return a clock that uses the best available system clock _in the UTC zone, not null
Obtains a clock that returns the current _instant using the best available system clock, converting to date and time using the UTC time-zone. !(p) This clock, rather than {@link #systemDefaultZone()}, should be used when you need the current _instant without the date or time. !(p) This clock is based on the best available system clock. This may use {@link System#currentTimeMillis()}, or a higher resolution clock if one is available. !(p) Conversion from _instant to date or time uses the {@linkplain ZoneOffset#UTC UTC time-zone}. !(p) The returned implementation is immutable, thread-safe and {@code Serializable}. It is equivalent to {@code system(ZoneOffset.UTC)}.
@return a clock that uses the best available system clock _in the UTC zone, not null