[packager] Default argument lambdas should be well behaved

The title is an attempt to be terse without putting the entire bug in the tile.

For all BundleParamInfo objects returned by com.oracle.tools.packager.Bundler#getBundleParameters, when a default value lambda that lambda should not throw any exceptions in typical executions.

* If a read-only params map is passed in that is not a typical execution and an exception is acceptable
* If an empty (but writable) map is passed in that is typical and no exception should result
* If a map containing valid values is passed then no exception should result.
* If an exception could result from a map containing invalid values, the description of the BundleParam or the javadoc should provide an explanation to the developer when and why.

Note that returning a null value for a default value lambda is acceptable and means that the value must be set by the consumer of the API.

�The only known exception at the moment is preferncesID, which either must be set or have an identifier set.