Bug 153412 Change parameter type will cause preview fail
Description: Change parameter type will cause preview fail Steps to reproduce: 1. New a report paramter, string, text-box, default value is abc. 2. Drag the parameter to Layout and preview. 3. Change the parameter's type to integer, list-box, add a value 1 4. Preview Expected result: No errors. Actual result: The value "abc" is invalid with the type "integer".
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/actionhandler/BirtCacheParameterActionHandler.java
handle.addConfigVariable( configVar );
					}
					continue;
				}
				
				parameter = (ScalarParameterHandle) attrBean
						.findParameter( paramName );
				
				
				if ( paramValue != null && parameter != null )
				{
					try
					{
						String pattern = parameter.getPattern( );
						String dataType = parameter.getDataType( );
						Object paramValueObj = ParameterValidationUtil
								.validate( dataType, pattern, paramValue,
										attrBean.getLocale( ) );
						
						
						if ( DesignChoiceConstants.PARAM_TYPE_STRING
								.equalsIgnoreCase( dataType ) )
						{
							pattern = null;
						}
						paramValue = ParameterValidationUtil.getDisplayValue(
								dataType, pattern, paramValueObj, ULocale.US );
					}
					catch ( Exception err )
					{