Remove XMLSerializer

[BobDu]

Ref: #35 (comment)

At the same time, the optional dependency xom has been removed.

Testing done

run mvn clean verify

[basil]

We might be able to do this if there are no transitive usages (--includePluginLibs) and no usages in proprietary CloudBees plugins. See https://www.jenkins.io/doc/developer/plugin-development/usage-in-plugins/.

[basil]

Making it explicit that this PR will not be accepted without results of passing usage-in-plugins transitive runs against both open-source Jenkins and CloudBees CI as documented in https://www.jenkins.io/doc/developer/plugin-development/usage-in-plugins/.

[BobDu]

pass usage-in-plugins to search api usages in plugin (about cloudbees ci plugin)

in addclass.txt file

net.sf.json.*
net.sf.ezmorph.*

run

mvn clean compile exec:java -Dexec.args="--includeCore -i -p -C addclass.txt --updateCenter https://jenkins-updates.cloudbees.com/update-center/envelope-core-oc/update-center.json?version=2.440.3.8,https://jenkins-updates.cloudbees.com/update-center/envelope-core-mm/update-center.json?version=2.440.3.8"

result has this plugin

alauda-pipeline
BlazeMeterJenkinsPlugin
cloudshell-sandbox
ec2-deployment-dashboard
environment-manager
label-linked-jobs
lotus-connections-plugin
micro-focus-performance-center-integration
requests
scripted-cloud-plugin
sms
test-results-aggregator

But when I read the source code of these plugins, haven't found any actual use of net.sf.json.xml package.