id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
19165	pbf plugin removes empty relations when saving to file	GerdP	Don-vip	"==== What steps will reproduce the problem?
1. Have a relation without members
2. Save as xyz.osm.pbf
3. Save as xyz.osm (xml format)
4. Load both files

==== What is the expected result?
Loaded content should be equal
==== What happens instead?
The pbf data doesn't contain the empty relation.
==== Please provide any additional information below. Attach a screenshot if possible.
Noticed this while working on #19136.
When I use osmconvert to convert the osm xml file to osm.pbf and load that file with JOSM the empty relation is shown.
{{{
URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-04-06 02:17:07 +0200 (Mon, 06 Apr 2020)
Build-Date:2020-04-06 00:18:43
Revision:16239
Relative:URL: ^/trunk

Identification: JOSM/1.5 (16239 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 1903 (18362)
Memory Usage: 811 MB / 1820 MB (612 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-XX:StartFlightRecording=name=MyRecording2,settings=d:\dbg\gerd.jfc, -XX:FlightRecorderOptions=defaultrecording=true,dumponexit=true,dumponexitpath=e:\ld\perf_20200428_140336.jfr]

Plugins:
+ OpeningHoursEditor (35414)
+ PolygonCutOut (v0.7)
+ apache-commons (35362)
+ buildings_tools (35405)
+ continuosDownload (91)
+ ejml (35313)
+ geotools (35169)
+ jaxb (35092)
+ jts (35122)
+ merge-overlap (35248)
+ o5m (35248)
+ opendata (35405)
+ pbf (35248)
+ poly (35248)
+ reverter (35409)
+ undelete (35405)
+ utilsplugin2 (35405)
}}}
"	defect	closed	normal		Plugin pbf		fixed	template_report