1. School of Computing, Newcastle University, Urban Sciences Building, Newcastle upon Tyne, NE4 5TG, UK
2. National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, USA
3. Department of Informatics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
4. HASLab - High-Assurance Software Laboratory / INESC TEC, Campus de Gualtar, 4710-057 Braga, Portugal