Log messages for mismatches between document type and prototype node

When child nodes are defined in document type definitions (e.g. hippo:html nodes or compound nodes) but those child nodes are not available in the prototype node, then the document editor in the channel manager cannot process that document type correctly. See the linked issue CHANNELMGR-1737.

To provide developers of client projects and of the channel manager code base with a clue about this situation, add error log messages that signal this problem.

Developers of client projects should not make manageContent buttons to create new documents of these types.