Why are timestamps in time series aware of timezones?

[erikd71]

So for context, I've been running into some issues drawing timeseries graphs with JFreeChart:

• It can get really slow with a lot of data points
• I got into issues (thrown exceptions) in places where timezone offset changes happened daylight saving times etc)

For the performance issue, what fixed most issues for me was simply using class FixedMillisecond instead of Millisecond for the timestamps in the time series.
For the second issue I got around it (without really fixing it) by calling TimeSeries.addOrUpdate() instead of TimeSeries.add().

But it seems to me that none of this should be an issue by design.

• A time series plot should IMHO not be aware of time zones or daylight saving times etc. The X-axis coordinates for the plot should just be the absolute time stamp regardless of where you are (like UTC time in milliseconds since epoch).
• Time zone offsets etc should IMHO only be represented in the labels on the time axis.

But perhaps I'm missing something?