On karaf distribution with netconf-connector-ssh (feature:install odl-netconf-connector-ssh) following warnings get dumped into karaf console:

Warning: org.apache.xerces.parsers.SAXParser: Feature 'http://javax.xml.XMLConstants/feature/secure-processing' is not recognized.
Warning: org.apache.xerces.parsers.SAXParser: Property 'http://javax.xml.XMLConstants/property/accessExternalDTD' is not recognized.
Warning: org.apache.xerces.parsers.SAXParser: Property 'http://www.oracle.com/xml/jaxp/properties/entityExpansionLimit' is not recognized.

upon sending this restconf request:

GET http://localhost:8181/restconf/config/opendaylight-inventory:nodes/node/controller-config/yang-ext:mount

and

POST http://localhost:8181/restconf/config/opendaylight-inventory:nodes/node/controller-config/yang-ext:mount/config:modules
with payload like:

<module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
<type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:openflow:common:config:impl">prefix:openflow-provider-impl</type>
<name>openflow-provider-impl</name>
<role xmlns="urn:opendaylight:params:xml:ns:yang:openflow:common:config:impl">BECOMEMASTER</role>
</module>

(change where this field in configuration is added: https://git.opendaylight.org/gerrit/#/c/12644/)

Despite of this it works and property change gets propagated to module.