<PackageReference Include="Google.Protobuf" Version="3.35.1" />

Google.Protobuf.ExtensionSet<TTarget>

public sealed class ExtensionSet<TTarget> where TTarget : IExtendableMessage<TTarget>
Used for keeping track of extensions in messages. IExtendableMessage<T> methods route to this set. Most users will not need to use this class directly
public ExtensionSet()

public int CalculateSize()

Calculates the size of this extension set

public void WriteTo(CodedOutputStream stream)

Writes the extension values in this set to the output stream

public void WriteTo(ref WriteContext ctx)

Writes the extension values in this set to the write context