Shibboleth IdP 3.1.2, jetty "idp.ini" keystore passwords format

[Alan Angulo (Office365 admin)]

Hello Shib Users, I have a quick question.
The keystore passwords in the jetty configuration file "idp.ini" seem to be in some sort of format encapsulated by curly brackets.
Can someone point me to the documentation about what type of format is the cleartext password supposed to be converted to (see below):

# Keystore passwords
jetty.backchannel.keystore.password= {4D510665-37EF-4F3A-8AF6-FCB20DA895A5}
jetty.browser.keystore.password= {561F03F5-B0B2-491F-84AE-84D22951DD3F}


Replacing jetty.browser.keystore.password with cleartext leads to the following error in the "commons-daemon" log:

[2015-09-28 23:42:13] [debug] ( javajni.c:888 ) [ 2592] argv[0] = jetty.base=C:\bin\Shibboleth\IdP3.1.2\\jetty-base
[2015-09-28 23:42:13] [debug] ( javajni.c:888 ) [ 2592] argv[1] = jetty.logs=C:\bin\Shibboleth\IdP3.1.2\\jetty-base\logs
[2015-09-28 23:42:13] [debug] ( javajni.c:888 ) [ 2592] argv[2] = STOP.PORT=8963
[2015-09-28 23:42:13] [debug] ( javajni.c:888 ) [ 2592] argv[3] = STOP.Key={10207D30-B4CA-4012-86BB-5EC330E2A487}
[2015-09-28 23:42:13] [debug] ( javajni.c:941 ) [ 2592] Java Worker thread started org/eclipse/jetty/start/Main:main
[2015-09-28 23:42:14] [debug] ( prunsrv.c:1186) [  292] Java started org/eclipse/jetty/start/Main
[2015-09-28 23:42:14] [info]  ( prunsrv.c:1284) [  292] Service started in 1109 ms.
[2015-09-28 23:42:14] [debug] ( prunsrv.c:844 ) [  292] reportServiceStatusE: 4, 0, 0, 0
[2015-09-28 23:42:14] [debug] ( prunsrv.c:1528) [  292] Waiting for worker to finish...
[2015-09-28 23:42:21] [debug] ( javajni.c:471 ) [ 1576] Exit hook with exit code -2
[2015-09-28 23:42:21] [debug] ( prunsrv.c:919 ) [ 1576] Start exit hook called ...
[2015-09-28 23:42:21] [debug] ( prunsrv.c:920 ) [ 1576] VM exit code: -2

Any hints will be very much appreciated.