business logic and 3d party library problem

i confused with add library to service api
i see this error:
what i do know?i need add 3d party library to service api
i attached my project to this topic
“code”: 0,
“message”: “Type:“java.lang.NoClassDefFoundError”, Description:“com/squareup/moshi/Moshi$Builder”\nExceptionClass:“ServiceException” {Msg:“none”, Cause:“none”}”
} (493.11kB)

Please take a look at this comment, where Mark, points to an example of a custom business logic project which uses third party libraries

You can download it, try if it works for you and add your own third-party libraries in the same way