Tip : Multiple markers at this line - Step definitions detection works only when the project is configured as cucumber project.

This is usually seen in the feature file as a warning message. 

If you install feature file plugin from eclipse market place and if you restart the tool, the existing feature files gets this warning. 

I've observed it in the following eclipse installation: 

Version: 2020-03 (4.15.0)

Build id: 20200313-1211

Right click on the eclipse project -> Configure -->  Convert to Cucumber Project...

References: 
https://stackoverflow.com/questions/58327032/step-definition-detection-only-works-when-project-is-configured-as-cucumber-proj