You start your process with this map.
This will get keys from the map, and put them into the process variable you have defined.
Then, in a task node, you have to map each process variable you will need to a node variable.
Then, when you are in work item handler, you will get the parameters you have defined for this node, not all process variables.
To make it more clear. If you are using Eclipse plugin,
1) Define "examOK" variable in process. Click on process->Properties->Variables, and then add this variable
2) Then, for example you have a custom node. Click on the node->Properties->Parameter Mapping, and then you put the name of the process variable, "examOK", and the name you will use it inside work item handler (it can be the same).
3) Then, with workItem.getParameter("examOK") should work.
Hope this helps,
Demian