Service DhcpRelay

HTTP Method	Resource	Request	Response	Description
`GET`	.../dhcp-relay/option_82	N/A	`DhcpRelayOption82`	Returns the DHCP Relay Option 82.
`PUT`	.../dhcp-relay/option_82	`DhcpRelayOption82`	`DhcpRelayOption82`	Updates the given DHCP Relay Option 82.

Attribute 'is_option82_enabled' in DhcpRelayOption82.json is updated with the default_value, false.