GeoJSON export error

[BrackoNe]

Hi all,

We have a problem in the process of exporting GeoJSON files using geojson (version 116).

If you try to export any polygon/area (closed way) to geojson it saves to LineString instead to Polygon. If I open GeoJSON file which I have exported from QGIS and it has following part:
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[]...}
it works well.
However, if you try to re-save the same file from JOSM, it will automatically save to LineString.

I'm trying to fix some lakes and forests, but as soon as I export geometry, it messes everything because this conversion.

Can you fix this issue or tell me how to bypass this problem?

Thanks in advance,
Nemanja

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: 2018-12-31 15:09:58 +0100 (Mon, 31 Dec 2018)
Build-Date:2018-12-31 14:24:10
Revision:14620
Relative:URL: ^/trunk

Identification: JOSM/1.5 (14620 en) Windows 10 64-Bit
OS Build number: Windows 10 Pro 1803 (17134)
Memory Usage: 1581 MB / 1820 MB (654 MB allocated, but free)
Java version: 1.8.0_144-b01, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 2560x1440, \Display1 2560x1440
Maximum Screen Size: 2560x1440
Dataset consistency test: No problems found

Plugins:
+ FastDraw (34867)
+ Mapillary (1.5.18)
+ RoadSigns (34867)
+ apache-commons (34506)
+ apache-http (34632)
+ buildings_tools (34904)
+ ejml (34389)
+ geojson (116)
+ geotools (34513)
+ imagery_offset_db (34867)
+ jaxb (34678)
+ jna (34867)
+ jogl (1.2.2)
+ jts (34524)
+ kendzi3d (1.0.205)
+ kendzi3d-resources (0.0.2)
+ log4j (34527)
+ mbtiles (a3e491d)
+ measurement (34867)
+ microsoft (1535663476)
+ opendata (34911)
+ splinex (34901)
+ tageditor (34867)
+ turnlanes (34678)
+ turnlanes-tagging (280)
+ turnrestrictions (34867)
+ utilsplugin2 (34915)

Tagging presets:
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_preset_JOSM/master/RS.zip

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/ParkingLanes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&zip=1
+ https://pasharm.github.io/New_basic_style_for_JOSM/New_basic_style.mapcss
- %UserProfile%\Desktop\TrafficSigns_edited2.zip
+ %UserProfile%\Desktop\beta_style_josm-master.zip
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_style_JOSM/master/Styles_Traffic_signs_EUR_OR.zip
+ %UserProfile%\Desktop\Microsoft-TurnRestriction.mapcss

Last errors/warnings:
- E: Error while reading json file!
- E: java.lang.ClassCastException: Cannot cast org.glassfish.json.JsonNumberImpl$JsonBigDecimalNumber to javax.json.JsonArray
- E: Error while reading json file!
- E: java.lang.ClassCastException: Cannot cast org.glassfish.json.JsonNumberImpl$JsonBigDecimalNumber to javax.json.JsonArray
- E: Error while reading json file!
- E: java.lang.ClassCastException: Cannot cast org.glassfish.json.JsonNumberImpl$JsonBigDecimalNumber to javax.json.JsonArray
- E: Error while reading json file!
- E: java.lang.ClassCastException: Cannot cast org.glassfish.json.JsonNumberImpl$JsonBigDecimalNumber to javax.json.JsonArray
- E: Error while reading json file!
- E: java.lang.ClassCastException: Cannot cast org.glassfish.json.JsonNumberImpl$JsonBigDecimalNumber to javax.json.JsonArray

[BrackoNe]

Example of geojson file with Polygon entity.