OptionalfilterOptional filter function to determine whether a layer should be included in the result.
Return false to exclude a layer (and all its children) from the result.
OptionalsortIf set to true, layers will be ordered by their display order:
Layers listed first in the returned array are shown below layers listed at a later index.
By default, layers are returned in arbitrary order.
These options can be used when recursively retrieving layers from a collection.