Why ObjectResult is used as return type of webget method in wcf dataservices

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i am reading wcf from here "https://docs.microsoft.com/en-us/dotnet/framework/data/wcf/how-to-define-a-service-operation-wcf-data-services"

and it says The method must return one of the following:

void(NothinginVisualBasic)IEnumerable<T>IQueryable<T>An entity type in the data model that the data service exposes.

A primitive class such as integer orstring.

but i can see webget is returning

[WebGet]publicSystem.Data.Objects.ObjectResult<dcHCGetCust>   getCusts(Nullable<long>CustId){returnthis.CurrentDataSource.uspGetCust(intProjectId);}

so please tel me what is it (objectResult) and where i can read it in wcf ( any link would be appreciatable)

yours sincerely

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