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
if ( matchDataType( cachedColumn ) )
			{
				columnChooser.add( cachedColumn.getColumnName( ) );
			}
		}
		if ( columnChooser.indexOf( originalSelection ) != -1 )
		{
			columnChooser.setText( originalSelection );
		}
		
		
		
		
		columnChooser.setEnabled( columnChooser.getItemCount( ) > 0 );
		updateMessageLine( );
	}
	private boolean matchDataType( ResultSetColumnHandle column )
	{
		String type = getSelectedDataType( );
		if ( type.equals( DesignChoiceConstants.PARAM_TYPE_STRING )
				|| DesignChoiceConstants.COLUMN_DATA_TYPE_ANY.equals( column.getDataType( ) ) )
		{
			return true;
		}
		if ( DesignChoiceConstants.COLUMN_DATA_TYPE_DATETIME.equals( column.getDataType( ) ) )
		{
			return type.equals( DesignChoiceConstants.PARAM_TYPE_DATETIME );
		}
		else if ( DesignChoiceConstants.COLUMN_DATA_TYPE_DECIMAL.equals( column.getDataType( ) ) )
		{