public static <T_ROW> Function<T_ROW, String> toStringFunc(final Function<T_ROW, Object> valueExtractor) {
        return (T_ROW row) ->
                NullSafe.toStringOrElse(row, valueExtractor, "");
    }
Returns a {@link Function} that will call the toString method on the value returned
from passing the row into valueExtractor, but only if the value is non-null.
stroom-core-client/src/main/java/stroom/util/client/DataGridUtil.java