Creating a mapping class for Android or iOS when the API specifications are fixed can be tedious.
The following two are often used. jsonschema2pojo jsonschema2pojo
WEB service that creates POJO (Plain Old Java Object) from json or json scheme
It can also be used as a command or gradle plugin.
If you want a Mac-only app, JSON Export is recommended. You can also create Swift and Objective-C models
If it is an in-house API, it is convenient because you can create it with Codegen if you define the API firmly with Swagger.
Reference: Easy management of RESTful API with Swagger