davmail package from the bionic repository does not start

[Norbert]

The below is what it shows on start:

```
$ davmail
Exception in thread "main" java.lang.UnsatisfiedLinkError: Can't load library: /usr/lib/jvm/java-11-openjdk-amd64/lib/libawt_xawt.so
 at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2630)
 at java.base/java.lang.Runtime.load0(Runtime.java:768)
 at java.base/java.lang.System.load(System.java:1837)
 at java.base/java.lang.ClassLoader$NativeLibrary.load0(Native Method)
 at java.base/java.lang.ClassLoader$NativeLibrary.load(ClassLoader.java:2442)
 at java.base/java.lang.ClassLoader$NativeLibrary.loadLibrary(ClassLoader.java:2498)
 at java.base/java.lang.ClassLoader.loadLibrary0(ClassLoader.java:2694)
 at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2648)
 at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:830)
 at java.base/java.lang.System.loadLibrary(System.java:1873)
 at java.desktop/java.awt.Toolkit$3.run(Toolkit.java:1399)
 at java.desktop/java.awt.Toolkit$3.run(Toolkit.java:1397)
 at java.base/java.security.AccessController.doPrivileged(Native Method)
 at java.desktop/java.awt.Toolkit.loadLibraries(Toolkit.java:1396)
 at java.desktop/java.awt.Toolkit.<clinit>(Toolkit.java:1429)
 at java.desktop/java.awt.SystemTray.isSupported(SystemTray.java:221)
 at davmail.ui.tray.DavGatewayTray.init(DavGatewayTray.java:232)
 at davmail.DavGateway.main(DavGateway.java:73)

```

Some more info:

```
$ ls /usr/lib/jvm/java-11-openjdk-amd64/lib/libawt_xawt.so
ls: cannot access '/usr/lib/jvm/java-11-openjdk-amd64/lib/libawt_xawt.so': No such file or directory

$ dpkg -S libawt_xawt.so
dpkg-query: no path found matching pattern *libawt_xawt.so*

https://packages.ubuntu.com/search?suite=bionic&arch=amd64&mode=exactfilename&searchon=contents&keywords=libawt_xawt.so shows that I need openjdk-11-jre-headless package installed

$ sudo apt-get install openjdk-11-jre-headless
[sudo] password for x:
Reading package lists... Done
Building dependency tree
Reading state information... Done
openjdk-11-jre-headless is already the newest version (11.0.11+9-0ubuntu2~18.04).
openjdk-11-jre-headless set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

```

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: davmail 4.8.3.2554-1
ProcVersionSignature: Ubuntu 4.15.0-143.147-generic 4.15.18
Uname: Linux 4.15.0-143-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.23
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Sat May 15 06:25:02 2021
InstallationDate: Installed on 2021-05-15 (0 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
SourcePackage: davmail
UpgradeStatus: Upgraded to bionic on 2021-05-15 (0 days ago)

[Matthias Klose (doko)]

please install openjdk-11-jre

[Norbert (nrbrtx)]

This fixes the issue, but it is strange that davmail does not depend on openjdk-11-jre .