If you have this error in jenkins console when you try to use sonar scanner try the next solution :
Error msg: You must define the following mandatory properties for ‘Unknown’: sonar.projectKey
projectKey is simply the unique identifier of your project inside SonarQube. You ahave to choose whatever you want, as long as it is unique.
Then try to set the same key into the sonar scanner config :
sonar.projectKey= 8131572732578c67a30dbc6313a681 // this is the created key sonar.projectVersion=1.0 sonar.projectName=projet_formation sonar.sources=src/main/java/ sonar.language=java