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/ParameterDialog.java
needSort.setEnabled( true );
		}
	}
	private void updateMessageLine( )
	{
		String errorMessage = validateName( );
		if ( errorMessage == null )
		{
			if ( !isStatic( )
					&& columnChooser != null
					&& columnChooser.getItemCount( ) == 0 )
			{
				errorMessage = ERROR_MSG_NO_AVAILABLE_COLUMN;
			}
			else if ( defaultValue == null
					&& ( PARAM_CONTROL_COMBO.equals( getSelectedControlType( ) ) || DesignChoiceConstants.PARAM_CONTROL_RADIO_BUTTON.equals( getSelectedControlType( ) ) ) )
			{
				
				if ( !canBeNull( ) || !containValue( null, null, COLUMN_VALUE ) )
				{
					
					
					errorMessage = ERROR_MSG_NO_DEFAULT_VALUE;
				}
			}
		}
		if ( errorMessage != null )
		{
			errorMessageLine.setText( errorMessage );
			errorMessageLine.setImage( ERROR_ICON );