Bug 121111 Bad event handler class name does not cause an error
Open a report design, open any Data Set's Property editor. Type in an invalid Java class name for the "Event Handler Class" property, say "aaa". Preview a report that uses that Data Set. The report executes normally. No error is shown. Event handlers are an integral part of a report design, and if a script handler class is not found, or if the handler throws a runtime exception, Report Engine should either stop the report execution, or show the error message in the generated report. (Tested with the 2005-12-15 nightly build)
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/GetParameterDefinitionTask.java
dataCache.put( parameterGroup.getName( ), null );
	}
	/**
	 * The second step to work with the cascading parameters. Get the selection
	 * choices for a parameter in the cascading group. The parameter to work on
	 * is the parameter on the next level in the parameter cascading hierarchy.
	 * For the "parameter to work on", please see the following example. Assume
	 * we have a cascading parameter group as Country - State - City. If user
	 * specified an empty array in groupKeyValues (meaning user doesn't have any
	 * parameter value), the parameter to work on will be the first level which
	 * is Country in this case. If user specified groupKeyValues as
	 * Object[]{"USA"} (meaning user has set the value of the top level), the
	 * parameter to work on will be the second level which is State in "USA" in
	 * this case. If user specified groupKeyValues as Object[]{"USA", "CA"}
	 * (meaning user has set the values of the top and the second level), the
	 * parameter to work on will be the third level which is City in "USA, CA"
	 * in this case.
	 * 
	 * @param parameterGroupName -
	 *            the cascading parameter group name
	 * @param groupKeyValues -
	 *            the array of known parameter values (see the example above)
	 * @return the selection list of the parameter to work on
	 */
	public Collection getSelectionListForCascadingGroup(
			String parameterGroupName, Object[] groupKeyValues )
	{
		CascadingParameterGroupHandle parameterGroup = getCascadingParameterGroup( parameterGroupName );
		if ( parameterGroup == null )
			return Collections.EMPTY_LIST;