Bug 149922 Image builder - URI and file source type are treated as same
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
* <li>XML_PROPERTY_TAG, if the property is xml;
	 * <li>METHOD_TAG, if the property is method;
	 * <li>PROPERTY_TAG, if the property is string, number, and so on.
	 * </ul>
	 * 
	 * @param prop
	 *            the property definition
	 * @return the tag of this property
	 */
	protected String getTagByPropertyType( PropertyDefn prop )
	{
		assert prop != null;
		assert prop.getTypeCode( ) != PropertyType.STRUCT_TYPE;
		switch ( prop.getTypeCode( ) )
		{
			case PropertyType.EXPRESSION_TYPE :
				return DesignSchemaConstants.EXPRESSION_TAG;
			case PropertyType.XML_TYPE :
				return DesignSchemaConstants.XML_PROPERTY_TAG;
			case PropertyType.SCRIPT_TYPE :
				return DesignSchemaConstants.METHOD_TAG;
			default :
				if ( prop.isEncryptable( ) )
					return DesignSchemaConstants.ENCRYPTED_PROPERTY_TAG;
				return DesignSchemaConstants.PROPERTY_TAG;
		}
	}
	/**
	 * Writes one property entry of an element.
	 *