Prepare

Download/Unpackage Solr rm -R solr-5.5.2 && wget http://archive.apache.org/dist/lucene/solr/5.5.2/solr-5.5.2.zip && unzip solr-5.5.2.zip && rm solr-5.5.2.zip
Start Solr in default cloud example solr-5.5.2/bin/solr -e cloud -noprompt -a "-Denable.runtime.lib=true"
Upload configset solr-5.5.2/bin/solr zk -upconfig -n config -d src/main/resources/conf -z localhost:9983
Create Blob Store curl 'http://localhost:8983/solr/admin/collections?action=CREATE&name=.system'
Create collection solr-5.5.2/bin/solr create -c collection -n config

Test

Build jar mvn clean package
Upload handler curl -X POST -H 'Content-Type: application/octet-stream' --data-binary @target/solr-cloud-lib-test-1.0.jar http://localhost:8983/solr/.system/blob/solr-cloud-lib-test
Check available handler versions curl http://localhost:8983/solr/.system/blob/solr-cloud-lib-test
Make collection aware of handler (version 1) curl http://localhost:8983/solr/collection/config -H 'Content-type:application/json' -d '{"add-runtimelib": { "name":"solr-cloud-lib-test", "version":1 }}'
Load the handler by using it curl http://localhost:8983/solr/collection/handler
Get info about the current handler curl 'http://localhost:8983/solr/collection/admin/mbeans?wt=json&key=/handler&cat=QUERYHANDLER'

Change component version to 2.0 (in both, the java class and maven project; could be done by plugin)
Build jar mvn clean package
Upload handler curl -X POST -H 'Content-Type: application/octet-stream' --data-binary @target/solr-cloud-lib-test-2.0.jar http://localhost:8983/solr/.system/blob/solr-cloud-lib-test
Make collection aware of handler curl http://localhost:8983/solr/collection/config -H 'Content-type:application/json' -d '{"update-runtimelib": { "name":"solr-cloud-lib-test", "version":2 }}'
Load the handler by using it curl http://localhost:8983/solr/collection/handler
Get info about the current handler curl 'http://localhost:8983/solr/collection/admin/mbeans?wt=json&key=/handler&cat=QUERYHANDLER'