Adding root certificate to KNIME

How can we add a root certificate (.pem) to KNIME (on Windows), so that it can connect to servers requiring this?

What I tried so far without success:

1.

Adding the certificate to Windows using mmc.exe - I am assuming the KNIME java vm does not “see” this?

1.

Adding the .pem cert file in “C:\Program Files\KNIME\plugins\org.knime.binary.jre.win32.x86641.8.0.252-b09\jre\bin”

using:

keytool -import -alias ourrootcert -keystore cacerts -file our-root-cert.pem

The result was “Certificate was added to keystore”, but still no joy.

I am trying to connect to an Elasticsearch server by the way, using the Elasticsearch Connector, that just says “Error connecting to Elasticsearch. Check your configuration”, and the connected Elasticsearch Console: “General SSLEngine problem”