Using Google firebase

[aang7]

Trying to authenticate a token generated by google firebase gets me the following error:

Problem getting signing keys from Open ID Connect provider (issuer). ConfigurationManager threw System.InvalidOperationException Message: IDX20803: Unable to obtain configuration from: 'System.String'.

I used the base project that is being used: https://github.com/bryanknox/AzureFunctionsOpenIDConnectAuthSample

and I commented these lines in the AzureFunctionsOpenIDConnectAuthSample\OidcApiAuthorization\OidcApiAuthorizationService.cs file:

var tokenValidationParameters = new TokenValidationParameters
{
//RequireSignedTokens = true,
ValidAudience = _audience,
//ValidateAudience = true,
ValidIssuer = _issuerUrl,
ValidateIssuer = false,
//ValidateIssuerSigningKey = true,
//ValidateLifetime = true,
IssuerSigningKeys = isserSigningKeys
};

I don't know why commenting these lines seems to work with that project... any idea?