Java class to represent the Offline enumerated type.
Documentation from the relevant specification:
The Offline AVP (AVP code 1008) is of type Enumerated. If the Offline AVP is embedded within a Charging-Rule-Definition AVP it defines whether the offline charging interface from the PCEF for the associated PCC rule shall be enabled. The absence of this AVP within the first provisioning of the Charging-Rule-definition AVP of a new PCC rule indicates that the default charging method for offline shall be used. If the Offline AVP is embedded within the initial CCR on command level, it indicates the default charging method for offline pre-configured at the PCEF is applicable as default charging method for offline. The absence of this AVP within the initial CCR indicates that the charging method for offline pre-configured at the PCEF is not available. If the Offline AVP is embedded within the initial CCA on command level, it indicates the default charging method for offline. The absence of this AVP within the initial CCA indicates that the charging method for offline pre-configured at the PCEF is applicable as default charging method for offline. The default charging method provided by the PCRF shall take precedence over any pre-configured default charging method at the PCEF.