No analysis triggered

I introduced SonarCloud in the following PR: But no analysis is triggered? Can anyone help?

Looks like you are not running sonar-scanner in the build script. See examples here:

Also note that external P/R are currently not supported with the sonarcloud addon on travis.

Unfortunately, adding sonar-scanner to the scripts section gives me the following error in Travis-CI:

$ sonar-scanner
sonar-scanner: command not found
The command "sonar-scanner" exited with 127.

See the PR here.

What is the definition of an external P/R in this context? Mine is a public PR.