But AssetManager enables to create new Asset. In my case, I already have the asset and I'm just creating a few new renditions for the asset. Please take a look at the code below.private static final String CONTENT_PATH = "/" + JcrConstants.JCR_CONTENT;private static final String DAM_THUMBNAIL_FORMAT...

Okay, I see. Maybe you could help me with pointing which process is responsible for changing property state from "processing" to "processed"?

Correct.I've created custom workflow step as implementation of com.adobe.granite.workflow.exec.WorkflowProcess. In this custom step I'm using classes I've described in the previous comment.

Hi,To create renditions I'm using com.day.image.Layer and its methods: resize() and crop(). After that, using InputStream from the layer I'm adding new rendition using com.day.cq.dam.api.Asset.addRenditionMethod().