Element.class has the following methods that have HighlightState argument:

• public String getText(HighlightState highlightState);
• public String getAttribute(String attr, HighlightState highlightState);
• public String getCssValue(String propertyName, HighlightState highlightState).

All of them call this.getJsActions().highlightElement() inside, i.e. without passing the highlightState.
As a consequence the element is highlighted even if called with HighlightState.NOT_HIGHLIGHT which might be quite important e.g. when there is a need to get an element border color via css.

It seems that passing the value to this.getJsActions().highlightElement(highlightState) should solve the issue.