Can not create delivrable and deliverable items at once

If we try to create a deliverable and add some deliverable items in the same time ( before saving the deliverable), the creation fails with:

Caused by: java.lang.ClassCastException: org.codehaus.jackson.node.ObjectNode cannot be cast to java.util.Map
at com.nuxeo.brand.management.operations.CreateProjectDeliverable$$Lambda$1682/1949083692.accept(Unknown Source)
at java.util.ArrayList.forEach(ArrayList.java:1249)
at com.nuxeo.brand.management.operations.CreateProjectDeliverable.addDeliverable(CreateProjectDeliverable.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)