How to install an older Eclipse plugin of SonarLint
Instead of using Eclipse Marketplace, use menu in Help → Install New Software. Add sonarlint URL:
http://eclipse.sonarlint.org/
and than uncheck "Show only the latest versions of available software".
You will see all available version of sonarlint. If you already have it installed with unexpected version, you need to uninstall it first in Help → Installation Details.
I had exactly the same issue. Here is how I managed it:
Ask Google for "sonarlint 2.1.0"
You'll find a page link to 2.1.0 - Bintray
You will be able to download a zip.
Then, this stack will help you install the zip from your disk.
Hope it helps!
The official zip files for legacy versions of SonarLint are here: https://binaries.sonarsource.com/SonarLint-for-Eclipse/releases/
After downloading the zip file, in Eclipse:
Help -> Install New Software -> Add -> Archive -> the zip file