Add units (nanoseconds) to HealthCheck.

[SLG]

I need to add a manual healtcheck in code. I found the com.github.dockerjava.api.model.HealthCheck:

return new HealthCheck()
                .withTest(Arrays.asList("CMD", "curl", "-f", url))
                .withStartPeriod(SECONDS.toNanos(60))
                .withInterval(SECONDS.toNanos(30))
                .withTimeout(SECONDS.toNanos(30))
                .withRetries(50);

However, I've no idea what the correct unit should be.
I've tried seconds (too small), millis (too small value too), micro (seems to work, but still timing out) and nanos (seems to be the correct one).

[eddumelendez]

Hi, Thanks for the PR! Yes, according to the docs is nanoseconds

[eddumelendez]

Thanks for your contribution, @SLG !