Please apply the same fix than what was done in MGNLREST-289, to AssetFocalWriter.
https://git.magnolia-cms.com/projects/MODULES/repos/rest/commits/fb4ed09d645a2c96d682334505abfae086830dff#magnolia-rest-content-delivery/src/main/java/info/magnolia/rest/reference/dam/AssetWriter.java
https://git.magnolia-cms.com/projects/INCUBATOR/repos/dam-focal/browse/magnolia-dam-focal-common/src/main/java/info/magnolia/rest/reference/dam/AssetFocalWriter.java#132-134