Bug 182673 No default value error message prompts incorrectly
Steps to reproduce: 1. New a report parameter; 2. Choose control type as Combo; 3. Choose parameter as dynamic type; Expected result: As the isRequired is false by default, parameter's default value can be null value. There should be no error message about no default value prompt. Actual result; Error messages prompts
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
import com.ibm.icu.util.ULocale;
/**
 * Cascading Parameter Dialog.
 */
public class CascadingParametersDialog extends BaseDialog
{
	private static final String CHOICE_NULL_VALUE = Messages.getString( "CascadingParametersDialog.Choice.NullValue" );
	private static final String CHOICE_BLANK_VALUE = Messages.getString( "CascadingParametersDialog.Choice.BlankValue" );
	
	private static final String CHOICE_SELECT_VALUE = Messages.getString( "CascadingParametersDialog.Choice.SelectValue" );
	private static final String LABEL_PARAMTER_PROMPT_TEXT = Messages.getString( "CascadingParametersDialog.Label.parameterPromptText" ); 
	private static final String LABEL_VALUES = Messages.getString( "CascadingParametersDialog.Label.values" ); 
	private static final String LABEL_GROUP_GENERAL = Messages.getString( "CascadingParametersDialog.Label.group.general" ); 
	private static final String LABEL_CASCADING_PARAMETER_NAME = Messages.getString( "CascadingParametersDialog.Label.cascadingParam.name" ); 
	private static final String LABEL_GROUP_PROMPT_TEXT = Messages.getString( "CascadingParametersDialog.Label.groupPromptText" ); 
	
	
	
	
	
	
	
	
	private static final String LABEL_PARAMETERS = Messages.getString( "CascadingParametersDialog.Label.parameters" ); 
	private static final String LABEL_GROUP_PROPERTIES = Messages.getString( "CascadingParametersDialog.Label.group.properties" ); 
	private static final String LABEL_PARAM_NAME = Messages.getString( "CascadingParametersDialog.Label.param.name" ); 
	private static final String LABEL_LIST_LIMIT = Messages.getString( "CascadingParametersDialog.Label.listLimit" ); 
	private static final String LABEL_DATA_TYPE = Messages.getString( "CascadingParametersDialog.Label.dataType" ); 
	private static final String LABEL_DISPLAY_TYPE = Messages.getString( "CascadingParametersDialog.Label.displayType" ); 
	private static final String LABEL_DEFAULT_VALUE = Messages.getString( "CascadingParametersDialog.Label.defaultValue" );