Implementing sObject Collection api

[dscataglini]

I'd like to implement the following api
https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/resources_composite_sobjects_collections.htm

How do we feel about the following interface

client.collection.get('sObject', id: [1,2,3], fields: %w[firstName, LastName])

client.collection_create(all_or_none = true) do |record|
    record.add("{sObjectType}", {attr: value})
  …
end

client.collection_update(all_or_none = true) do |record|
    record.add("{sObjectType}", "{Id}", {attr: value})
  …
end

client.collection_upsert("{sObjectType}", external_id, all_or_none = true) do |record|
  record.add("{external_id}", {attr: value})
  …
end

client.collection.delete(ids = [], all_or_none = true)