Explanation/Reference:
From JSR318 - Enterprise JavaBeans 3.1, Final Release
4.9.6 Business Methods
The business method must be declared as public.
4.9.7 Session Bean's Business Interface
If the bean does not expose any other business interfaces (Local, Remote) or No-Interface view, and the bean class implements a single interface, that interface is assumed to be the business interface of the bean. This business interface will be a local interface unless the interface is designated as a remote business interface by use of the Remote annotation on the bean class or interface or by means of the deployment descriptor.
4.9.8 Session Bean's No-Interface View
If the bean exposes at least one other client view, the bean designates that it exposes a no-interface view by means of the @LocalBean annotation on the bean class or in the deployment descriptor.
All public methods of the bean class and any superclasses are exposed as business methods through the no-interface view