The Cargo port checker is useful as it checks whether ports are in use before starting a container - Which avoids dark issues later on. Unfortunately, in case a properties file is used for Cargo and for external services, Cargo can check port numbers outside its scope. For example, one could be defining one file with all port numbers:
... and Cargo will check the servlet, AJP and RMI ports (which is good), and the SMTP port (which doesn't name sense).
Only check port numbers for configuration properties prefixed with cargo. to avoid this issue.