Bug 163271 Cascading parameter dialog - Changing from multiple to single dataset does not work
Steps to reproduce - - Create a new cascading parameter group - Select multiple dataset - define parameter country and associate it with datasetCountry - define parameter state and associate with datasetSate Now try to change from multiple dataset to single dataset. The second dataset still shows up and also the report design file is wrong. The single dataset should be saved ast he cascading parameter group level.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/GetParameterDefinitionTask.java
return;
			}
			catch ( BirtException ex )
			{
				ex.printStackTrace( );
			}
		}
		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