This class is used to read the user's timezone preference from adf configuration file. The xml element user-timezone must have an attribute "expression" that contains an EL expression that when evaluated returns the user's timezone preference.
The method will parse the expression attribute of a user-timezone element from the web-inf/adf-config.xml file. The method ignores any previous results stored for this namespace.
currentCtx - the current context available at the time of parsing.