Calling StdLib.JsonSerialize on a contract manifest returns error "Specified cast is not valid."

[csmuller]

Describe the bug

Calling StdLib.JsonSerialize on a contract manifest returns error "Specified cast is not valid."

To Reproduce

• Create, compile, deploy the following contract:

    public class ExampleContract : SmartContract
    {
  
        public static object method()
        {
            Contract c = ContractManagement.GetContract(NEO.Hash);
            return StdLib.JsonDeserialize(c.Manifest);
        }
    }

• Run neo-express: neoxp reset -f && neoxp run
• Deploy the contract: neoxp contract deploy bin/sc/ExampleContract.nef genesis
• Invoke the method:
  • Create an invoke file:

    [
        {
            "contract": "ExampleContract",
            "operation": "method",
            "args": []
        }
    ]

  • Run neoxp contract invoke invoke.json genesis

Expected behavior
As mentioned in this PR's discussion, it should be easy to replace the contract name in a manifest with a new name by, e.g., using StdLib.jsonSerialze.

Platform:

• OS: MacOS 11.4
• Version nccs 3.0.2, neoxp 3.0.5

[irshadnilam]

To add to this,
without having an ability to change the manifest name, it is difficult to create a factory contract in NEO.

[roman-khimov]

c.Manifest is not a string since #2254, that's why it fails. At the same time if we're talking about factories why do need to take manifest from GetContract, why factory doesn't have it stored internally?

[csmuller]

Great, thanks @roman-khimov. We missed that change.
@shargon, The dotnet devpack needs this update as well, AFAIK.