After migrating Website Content to 4.5.7, I've to change the old paragraphs jcr:primaryTpye from "mgnl.contentNode" to "mgnl:component"

<sv:node sv:name="0"> <- this is a paragraph
<sv:property sv:name="jcr:primaryType" sv:type="Name">
<sv:value>mgnl:contentNode</sv:value>
</sv:property>

So I wrote a little script which finds me all paragraphs. When trying

node.setProperty("jcr:primaryType", "mgnl:component");

it always results in a "javax.jcr.nodetype.ConstraintViolationException: Unable to perform operation. Node is protected."

same with
MigrationUtil.updatePropertyIfExist(node, propertyName, oldValue, newValue)

For a proper migration it is necessary to update those nodes types.

How to perform this action with the Magnolia Migration Tool.