参考：

http://***.com/questions/588524 / return-unknown-generic-listt [ ^ ]

http://***.com/questions/8016233/in-c-how-do-i-call-a-function-that-is-returning-a-list [ ^ ]

这可能会有所帮助。

Refer:
http://***.com/questions/588524/return-unknown-generic-listt[^]
http://***.com/questions/8016233/in-c-how-do-i-call-a-function-that-is-returning-a-list[^]
This may help.

而不是list< object>尝试列表< customer>并返回相同，因为它已经是已知对象

instead list<object> try list<customer> and return the same because it is already known object