[DSL] Expose ColorUtil methods to DSL rules

[holgerfriedrich]

• Expose xyToKelvin and kelvinToXY
• Add missing throws declaration
• Expose xyToDuv

Unfortunately, we forgot about the throws declaration in #4367. This is API breaking, you might need to add a catch statement in binding code.

[andrewfg]

LGTM many thanks.

[holgerfriedrich]

Lets wait for #4401, then we can add xyToDuv as well.

[holgerfriedrich]

Done.
I will create an additional PR in docs.
@florian-h05 do you want to create a change in JS scripting as well (follow-up to openhab/openhab-js#319)?

[florian-h05]

These methods are just added to the CoreUtil class, correct?
In that case only a doc update in openhab-js is needed.

[andrewfg]

@holgerfriedrich apropos the thrown exception potentially breaking the API — two things..

1. In [zigbee] Map colour temperature states to color HSB states org.openhab.binding.zigbee#855 I did not call the respective method, so that one will not be broken.
2. Did you check the ColorUtil JUnit tests (here in core) since they do call the respective method?

openhab-core/bundles/org.openhab.core/src/test/java/org/openhab/core/util/ColorUtilTest.java

Line 665 in 963a8d1

void testKelvinXyConversion() {

[holgerfriedrich]

@andrewfg thanks for checking, the build seems still fine. I think in tests it is not mandatory to catch all declared exceptions....