ToString() on empty StringBuilder

What is returned by ToString() if no text was added to the StringBuilder, meaning if no Append*() or Insert() had been called? Will it return null or ""?

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* ID: ec97ffa5-4254-b02a-3e7b-34ff702071dc
* Version Independent ID: 074dc3c2-38e4-673e-0ef9-a3497771d63f
* Content: [StringBuilder.ToString Method (System.Text)](https://docs.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.tostring?view=netframework-4.7.2)
* Content Source: [xml/System.Text/StringBuilder.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Text/StringBuilder.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**