id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
20489	"Test ""Water area inside water area"" doesn't work well"	GerdP	GerdP	"==== What steps will reproduce the problem?
1. Have a natural=water area inside another natural=water 
2. Select nothing and run validator (should produce warning)
3. Select the outer way and run validator (should produce warning)
4. Select the inner way and run validator 

==== What is the expected result?
4. should also produce a warning, like with building inside building
==== What happens instead?
4. doesn't produce a warning
==== Please provide any additional information below. Attach a screenshot if possible.
The bigger problem is when you draw a new polygon inside an existing one and press upload -> No warning.
If I got that right the problem is the usage of the `∈` operator in combination with the water_area class. If `∈` is replaced by `⊇` everything works fine.
{{{
URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-12-28 22:03:23 +0100 (Mon, 28 Dec 2020)
Build-Date:2020-12-30 02:30:55
Revision:17428
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17428 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2004 (19041)
Memory Usage: 1036 MB / 3641 MB (830 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→32×32, 32×32→32×32
VM arguments: [-XX:StartFlightRecording=name=MyRecording2,settings=d:\dbg\gerd.jfc, -XX:FlightRecorderOptions=defaultrecording=true,dumponexit=true,dumponexitpath=e:\ld\perf_20210215_150952.jfr]
Dataset consistency test: No problems found

Plugins:
+ buildings_tools (35669)
+ o5m (35640)
+ pbf (35650)
+ poly (35640)
+ reltoolbox (35640)
+ reverter (35688)
+ undelete (35640)
+ utilsplugin2 (35691)

Validator rules:
+ c:\josm\core\resources\data\validator\geometry.mapcss
}}}
"	defect	closed	normal	21.02	Core validator		fixed	template_report	Klumbumbus skyper