Certificate file difference between COPY and ADD

Hello,
My need is to import certificates (pem, cer) inside docker container so that JBoss can use it. I am using below code to import the files I received from vendor.

ADD certificate.pem /opt/jboss/cert.pem
ADD certificate.cer /opt/jboss/apicert.cer
RUN update-ca-trust

The above code copies the files inside container “/opt/jboss” but there is nothing present in “/etc/pki/ca-trust/source/anchors/”

But if I use COPY instead of ADD then I do not see any file inside “/opt/jboss”. But I see a file created as “yourcertificate.pem” inside “/etc/pki/ca-trust/source/anchors/”.

Can anybody explain me why is this? Also which one I am supposed to use so that JBoss can access and configure the certificate? Thanks.

Jboss as in Wildfly application server?
Also, are you trying to provide a “server certificate” or just the public part of a certificate for a different server/ca to prevent ssl verification errors when downloading files with curl/wget?