SpringBoot doesn't recognize RestController from another module in multi module Java application

The Spring Boot main application is in the core module, which does not have a dependency on the webgateway module. Therefore the class with the controller will not be present at runtime and can not be discovered by spring.

Fix: Add dependency to the webgateway to the core or move the launcher/main class to the webgateway module.

You can also use a third module that does the launching and has the dependencies to core and webgateway.