<PackageReference Include="Azure.Storage.Blobs" Version="12.27.0-beta.1" />

Azure.Storage.Blobs.Models.AppendBlobRequestConditions

Specifies append blob specific access conditions.
public long? IfAppendPositionEqual { get; set; }

IfAppendPositionEqual ensures that the AppendBlock operation succeeds only if the append position is equal to a value.

public long? IfMaxSizeLessThanOrEqual { get; set; }

IfMaxSizeLessThanOrEqual ensures that the AppendBlock operation succeeds only if the append blob's size is less than or equal to a value.