I don't have the time to make a good documentation but to create a custom provider you have to:
Create a object Kotlin class in app/src/main/java/com/tanasi/streamflix/providers
Extend your newly created object with Provider interface
Implement all methods (personally I use Retrofit to retrieve data)
Facultative: To retrieve video source it could be necessary to create an extractor in app/src/main/java/com/tanasi/streamflix/extractors extending Extractor interface
Summary
How can I put my own provider , and what is the json structure thanks
Please confirm the following