permissionValues property
The permissions granted to the grantee. SEND_AS allows the grantee to send email as the owner of the mailbox (the grantee is not mentioned on these emails). SEND_ON_BEHALF allows the grantee to send email on behalf of the owner of the mailbox (the grantee is not mentioned as the physical sender of these emails). FULL_ACCESS allows the grantee full access to the mailbox, irrespective of other folder-level permissions set on the mailbox.
Implementation
final List<PermissionType> permissionValues;