getExpandFilters(fnFilter) {
			return Object.keys(this.mPredicate2ExpandInfo).filter(fnFilter)
				.map((sPredicate) => this.mPredicate2ExpandInfo[sPredicate].filter);
		}
Returns an unsorted list of filter strings for the "$filter" system query option for all
nodes which contribute to the "ExpandLevels" parameter and where the given filter
function is matching.

@param {function(string):boolean} fnFilter - A filter function for the predicates
@return {string[]} The filter strings

@public