Last modified date be updated when any association/dissociation occurs
One of the strategies to sync Hubspot and any database is using the property 'hs_lastmodifieddate'.
The idea is to use the search endpoint and return just the objects that has 'hs_lastmodifieddate' after then last sync. So the sync is fast and cheap.
The problem is that when user associates/dissociates any object, the property 'hs_lastmodifieddate' doesn't update, excecpt in cases where the property "number of associated X" exists. For instance, when a contact and deal are associated, the property "number of associated contacts" on deal is updated and, then, the 'hs_lastmodifieddate' updates (due to property change, not association).
The other solution to that is always read all records for syncing, to ensure all associations are updated, the problem with that endpoint is that when the number of properties is too long it raises 414 error (the search api does not requires properties as params in URI).
