Bug 153378 [Regression]Label text won't show up when the text key is not found
Steps to reproduce: 1.Add a label, set text to "aaa" 2.Add a resource file "a" to the report, add a text key "k1" which is not in the a.properties to the label 3.Preview in Web Viewer Expected result: Label display "aaa" when the text key is not found Actual result: Nothing in preview
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/util/ParameterValidationUtil.java
* </ul>
	 * 
	 * @param dataType
	 *  		the data type of the input value
	 * @param format
	 *  		the format pattern to validate
	 * @param value
	 *  		the input value to validate
	 * @param locale
	 *  		the locale information
	 * @return the formatted string
	 */
	static public String getDisplayValue( String dataType, String format,
			Object value, ULocale locale )
	{
		if ( value == null )
			return null;
		if ( StringUtil.isBlank( format ) )
		{
			return getDisplayValue( dataType, value, locale );
		}
		if ( DesignChoiceConstants.PARAM_TYPE_DATETIME
				.equalsIgnoreCase( dataType )
				|| value instanceof Date )
		{
			DateFormatter formatter = new DateFormatter( locale );
			formatter.applyPattern( format );
			return formatter.format( (Date) value );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_FLOAT