Describe the bug
Duplicate com.sun.xml.bind installed which prevent other plugins to load Mylyn is good example.

To Reproduce
Install vanilla STS 4.9.0
install Mylyn from eclipse market place and restart
Open Task Repositories view for example
Eclipse still have original plugin com.sun.xml.bind_2.2.0.v201505121915.jar
Install Timekeeper 2 from https://resheim.net/p2/eclipse-timekeeper_beta/ and restart
It will install com.sun.xml.bind_2.3.3.v20201118-1818.jar and now eclipse has both 2.3.3 and 2.2.0 version of the plugin.
Open Task Repositories view is not working as well as Workweek from timekeeper.

The same happens if you install following plugin from Mylyn (https://download.eclipse.org/mylyn/releases/latest)
Mylyn Builds Connector: Hudson/Jenkins 1.17.0.v20200730-1155 org.eclipse.mylyn.hudson.feature.group Eclipse Mylyn
instead of timekeeper

I have tried the same with latest Eclipse and it behaves the same but all both plugins are working well.

Running on
java 15 2020-09-15
Java(TM) SE Runtime Environment (build 15+36-1562)
Java HotSpot(TM) 64-Bit Server VM (build 15+36-1562, mixed mode, sharing)