symbolSortKey
The default symbolSortKey for all annotations added to this annotation manager if not overwritten by individual annotation settings.
Sorts features in ascending order based on this value. Features with lower sort keys are drawn and placed first. When icon-allow-overlap or text-allow-overlap is false, features with a lower sort key will have priority during placement. When icon-allow-overlap or text-allow-overlap is set to true, features with a higher sort key will overlap over features with a lower sort key.