The deployment.* properties' values are visibility is not common across the deployment products Java Web start and Java Plug-in. Currently , SQE uses these values during the test suite execution at runtime locate for example the cache directory and other properties for verification purposes.

In Plug-in the deployment.* properties are exposed where as in Java Web Start these are not exposed and determined internally.So this is not consistent across both the deployment products,Another example for this would be when dumped the system properties in console Plug-in or Java Web Start all the properties are shown but cannot get the same values through System.getProperties() where as the same can be retrieved in Java Plug-in.

SQE needs a common hook/mechanism to get the System Propeties in Java Plug-in and Java We Start for internal purpose for all the properties used internally could be via deployment.config or deployment.properies based on the precedence.

I am attaching the email thread of discussion for background with suggestions from stanley and andy) with this bug report for the reference.(please see cooments section)