Bug 179743 Parameter Validate Event is not Called
I have tested the validate event on parameters and it never appears to get called.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
if ( !visitParameterGroup( (ParameterGroupHandle) param,
							value ) )
					{
						return false;
					}
				}
				else if ( param instanceof ScalarParameterHandle )
				{
					if ( !visitScalarParameter( (ScalarParameterHandle) param,
							value ) )
					{
						return false;
					}
				}
			}
			return true;
		}
	}
	protected IQueryResults executeDataSet( DataSetHandle hDataSet,
			HashMap parameters )
	{
		return null;
	}
	/**
	 * use the user setting parameters values to setup the execution context.
	 * the user setting values and default values are merged here.
	 */
	protected void usingParameterValues( )
	{
		if ( !parameterChanged )