FULL PRODUCT VERSION :
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Client VM (build 24.45-b08, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
according to jnlp specification the property-element 'defines a system property that will be available through the System.getProperty and System.getProperties methods' in the web start application.

this does not work in java 7 update 45.
system properties are not set.

it seems that only system properties are set if key starts with 'jnlp'.

REGRESSION. Last worked in version 7u40

ADDITIONAL REGRESSION INFORMATION:
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Client VM (build 24.45-b08, mixed mode, sharing)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
create a simple java web start application.
deploy a .jnlp file with 2 property-elements.

set the 1st property key to 'jnlp.test.1'.
set the 2nd property key to to 'xnlp.test.2'.

start the web start application.
use jvisualvm to list to system properties of the application.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
system property 'jnlp.test.1' and 'xnlp.test.2' should be listed.
ACTUAL -
only system property jnlp.test.1 is listed.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
set the required as argument in the application desc in jnlp.
in the application set the arguments as system property.