Java Platform, Enterprise Edition (Java EE) 8
The Java EE Tutorial
A managed bean is implemented by a Java class, which is called its bean class. A top-level Java class is a managed bean if it is defined to be a managed bean by any other Java EE technology specification, such as the JavaServer Faces technology specification, or if it meets all the following conditions.
It is not a nonstatic inner class.
It is a concrete class or is annotated
It is not annotated with an EJB component-defining annotation or
declared as an EJB bean class in
It has an appropriate constructor. That is, one of the following is the case.
The class has a constructor with no parameters.
The class declares a constructor annotated
No special declaration, such as an annotation, is required to define a managed bean.