最病 Versioning a Versioning raises some fundamental questions about the identity of a class, including what constitutes a compatible change o a compatible change is a change that does not affect the contract between the class and its callers Institute of Computer Software 2021/1/28 Nanjing UniversityVersioning  Versioning raises some fundamental questions about the identity of a class, including what constitutes a compatible change.  A compatible change is a change that does not affect the contract between the class and its callers. 2021/1/28 Institute of Computer Software Nanjing University 34