See: Description
| Interface | Description | 
|---|---|
| DescriptorBean | 
 The DescriptorBean interface is implemented by every bean in a descriptor
 bean graph. 
 | 
| SettableBean | 
 A bean which implements this interfaces supports the isSet and unSet methods
 such that a caller can test if a bean has been changed from its default value
 and also cause the value to be set back to the default. 
 | 
| Exception | Description | 
|---|---|
| BeanAlreadyExistsException | 
 Thrown when an attempt is made to create a bean with a key that already
 exists. 
 |