Determine the SymStore hash for the pdb matching a dll

I'm currently setting up some build infrastructure and as part of this process a .NET solution gets built and the symbols are stored in a SymbolSource server. I want to be able to test that Visual Studio will be able to successfully fetch the symbols from the server later. During a normal debugging session, the symbols will be fetched from the server by looking up the SymStore hash, but I can't figure out how it finds that hash. I want to extract it from the dll so I can manually try and fetch symbols from the server and build it into my testing.

Example SymbolSource url: http://myserver.com/SymbolSource/Newtonsoft.Json.pdb/03B6CF6C0E2A41A4B7EDDA4A3856180B1/Newtonsoft.Json.pdb

SymStore hash: 03B6CF6C0E2A41A4B7EDDA4A3856180B1

I can't find this hash inside the dll (Newtonsoft.Json.dll), and it's not the SymStore hash of the dll itself as far as I can tell.