How long do junior developers take to remove technical debt items?

Background. Software engineering is one of the engineering fields with the highest inflow of junior engineers. Tools that utilize source code analysis to provide feedback on internal software quality, i.e. Technical Debt (TD), are valuable to junior developers who can learn and improve their coding skills with minimal consultations with senior colleagues. Objective. We aim at understating which SonarQube TD items junior developers prioritize during the refactoring and how long they take to refactor them. Method. We designed a case study with replicated design and we conducted it with 185 junior developers in two countries, that developed 23 projects with different programming languages and architectures. Results. Junior developers focus homogeneously on different types of TD items. Moreover, they can refactor items in a fraction of the estimated time, never spending more than 50% of the time estimated by SonarQube. Conclusion. Junior Developers appreciate the usage of SonarQube and considered as a useful tool. Companies might ask junior developers to quickly clean their code.Peer reviewe