ClassNotFoundException for StatEt Eclipse plugin / RJ. Compatibility issue with Java9?

I installed RJ for StatEt with:

> install.packages(c("rj", "rj.gd"), repos="http://download.walware.de/rj-2.1")
Installiere Pakete nach 'C:/Users/eis/Documents/R/win-library/3.4'
(da 'lib' nicht spezifiziert)
versuche URL 'http://download.walware.de/rj-2.1/bin/windows/contrib/3.4/rj_2.1.0-13.zip'
Content type 'application/zip' length 342681 bytes (334 KB)
downloaded 334 KB

versuche URL 'http://download.walware.de/rj-2.1/bin/windows/contrib/3.4/rj.gd_2.1.0-2.zip'
Content type 'application/zip' length 97222 bytes (94 KB)
downloaded 94 KB

Paket 'rj' erfolgreich ausgepackt und MD5 Summen abgeglichen
Paket 'rj.gd' erfolgreich ausgepackt und MD5 Summen abgeglichen

Die heruntergeladenen Binärpakete sind in 
    C:\Users\eis\AppData\Local\Temp\Rtmp0G5hW5\downloaded_packages

After that my package description of rj is:

> packageDescription("rj")
Encoding: UTF-8
Package: rj
Version: 2.1.0-13
Title: RJ - R Package for high-level Java-R library RJ
Author: Stephan Wahlbrink, Tobias Verbeke, low-level R binding based on
        the JRI library by Simon Urbanek
Maintainer: Stephan Wahlbrink <stephan.wahlbrink@walware.de>
Depends: R (>= 2.11.0)
Suggests: rj.gd
SystemRequirements: java
Description: Server implementation and R functions for the high-level
        Java-R library RJ.  The package also includes callback
        functions for StatET.  It is shipped with an adapted version of
        the JRI library.  The package can be used only when R was
        loaded via RJ.
License: LGPL (== 2.1)
URL: http://www.walware.de/goto/opensource
NeedsCompilation: yes
Packaged: 2017-05-10 08:22:44 UTC; build
Built: R 3.4.0; x86_64-w64-mingw32; 2017-05-10 08:25:27 UTC; windows

-- File: C:/Users/eis/Documents/R/win-library/3.4/rj/Meta/package.rds

And I added the folder

C:/Users/eis/Documents/R/win-library/3.4

to R_LIBS in the StatEt Eclipse preferences:

When I try to start my console run configuration using RJ I get following error:

Fehler: Hauptklasse de.walware.rj.server.RMIServerControl konnte nicht gefunden oder geladen werden
Ursache: java.lang.ClassNotFoundException: de.walware.rj.server.RMIServerControl

I use

Windows 7
Java JDK 9.01,
Eclipse for JavaScript and Web Developers, Version: Oxygen.2 Release (4.7.2)
StatET 3.6.1
R version 3.4.3

version _
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 4.3
year 2017
month 11
day 30
svn rev 73796
language R
version.string R version 3.4.3 (2017-11-30) nickname Kite-Eating Tree

=> Is RJ for StatEt compatible to Java9?

=> If so, how can I correctly install RJ for StatEt?

=> How/where do I run R CMD javareconf on windows? I tried in bin folder of r but the argument javareconf is not known.