[Output Only] The resource that configures and manages this BGP
peer. - MANAGED_BY_USER is the default value and can be managed by
you or other users - MANAGED_BY_ATTACHMENT is a BGP peer that is
configured and managed by Cloud Interconnect, specifically by an
InterconnectAttachment of type PARTNER. Google automatically
creates, updates, and deletes this type of BGP peer when the PARTNER
InterconnectAttachment is created, updated, or deleted.