我正在定义一个用于JSimpledB（持久性库）的适配器班级这是GoogleGuavaConverter作为构造函数参数：sharedclassRoleConverter()extendsConverter(){sharedactualRoledoBackward(String?name){"Cannotconvertnulltorole."assert(existsname);returnRole.ofName(name);}sharedactualStringdoForward(Role?role){returnrole?.nameelse"null";}}sharedclassRoleT