When you want to pull content data from a schema field to the API calls section in ClientLibrary, you can fill the relevant model with a fluent parameter or with the data related to its relationships with an attribute.
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Example:
For example: by adding an attribute to the relevant property in the data model class, you can specify that this is a reference field and
[ReferenceField(Resolve=true)]
public Blabla TestData {get;set;}
When xContentClient.GetAsnyc() is called, the reference data can be loaded.
Another alternative is to fill these reference fields with the use of xContentClient.WithReference(m => m.TestData, m.XData).GetAsnyc();