`area:highway` is not detected as being an area, causing the validator to be wrong.

[GoodClover]

What steps will reproduce the problem?

1. Create a way with area:highway=*.
2. Create a way with landuse=*.
3. Ensure the ways are at least 4 nodes (below 4 will not get detected as an error).
4. Run the validator.

What is the expected result?

Nothing.
JOSM will not complain, detecting that area:highway=* means it is an area, which are allowed to share segments.

What happens instead?

JOSM complains that "Ways share segment with area" between the landuse and area:highway.
I assume this is because JOSM dosen't detect area:highway and thinks it is a way and not an area.

Example

Attached is an example of data that will cause the issue.

Please provide any additional information below. Attach a screenshot if possible.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-11-21 14:56:29 +0100 (Sat, 21 Nov 2020)
Build-Date:2020-11-22 02:30:52
Revision:17329
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17329 en_GB) Windows 10 64-Bit
OS Build number: Windows 10 Home 2009 (19042)
Memory Usage: 388 MB / 989 MB (85 MB allocated, but free)
Java version: 1.8.0_261-b12, Oracle Corporation, Java HotSpot(TM) Client VM
Look and Feel: com.formdev.flatlaf.FlatDarculaLaf
Screen: \Display0 1920x1080 (scaling 1.0x1.0)
Maximum Screen Size: 1920x1080
Best cursor sizes: 16x16 -> 32x32, 32x32 -> 32x32
Dataset consistency test: No problems found

Last errors/warnings:
- 00011.943 W: Failed to delete outdated plugin '<josm.pref>\plugins\flatlaf.jar'.
- 00011.944 W: Failed to install already downloaded plugin 'flatlaf'. Skipping installation. JOSM is still going to load the old plugin version.
- 12172.035 W: org.openstreetmap.josm.data.osm.search.SearchParseError: Unexpected token: <equals>

[GoodClover]

Sorry I mistyped in step 3.
Should say:

3. Ensure the ways share are at least 4 nodes (below 4 will not get detected as an error).

[GerdP]

I think this doesn't happen with tested version r17428, please update.

[GerdP]

Was fixed with r17350

[Don-vip]

Marked as duplicate of #20031.
Please update to current version of JOSM!