How to GET the applied backgroundcolor from a Row and a Cell of Vaadin Tree

Im using the Vaadin version 8.6.4 for Java and I have a dataset that is represented on a TreeGrid. Until now I could not get the styleName that is applied to any row or any cell. There is any method or trick to get the actual style of a cell/row in vaadin? The list of styles are added like the code that is below. And the function setStyleGenerator is called for each row/column that needs the desired style (defined in mainPageStyles)

I though also setting an Id to all cells before the Grid get created by overrideing the intern method of Grid Class. After that i should be able to fired a Javascript function on the client-side for searching the style of a cell by its id. But all that has been so complicated, so I have not been successful.

	final String reservationColor  = "background-color: "green" !important;";   
	final String STYLENAME_RESERVED = "reserved";

	Styles mainPageStyles = Page.getCurrent().getStyles();
	mainPageStyles.add(".v-treegrid-cell." + STYLENAME_RESERVED +"{"+ reservationColor + "}");