NETCONF ignores modules with submodules if device does neither support yang-library nor netconf-monitoring

I am following description from:
http://docs.opendaylight.org/en/stable-carbon/user-guide/netconf-user-guide.html

I am trying to open the URL:
http://localhost:8181/apidoc/explorer/index.html

The device has one configuration module including many sub-modules. It does neither support rfc6022 (netconf-monitoring) nor rfc7895 (yang-library) yet. All modules are declared in the <hello> exchange. As per rfc6020 submodules are not contained as in the capability exchange. All modules and sub-modules have been imported to the ODL schema-cache using the correct naming. Revisions seem to be correct.

From my understanding patching the <yang-module-capabilities> does not help, as this is to add capabilities missed during the hello-exchange. In conclusion, this is for modules only (not covering sub-modules).

When removing all the include statements from the configuration module (and all references to the corresponding sub-modules), the module is loaded (but almost empty).

Unclear if this is the expected behavior. Logging (even enabled to DEBUG level) does not contain any helpful information. The module is just ignored.

Please come up with a workflow, how to deal with such situations or fix the implementation (likely related to org.opendaylight.netconf.sal-rest-docgen).