public void AssertHasClientCredentials()
{
if (ClientId == null)
{
throw new ConfigurationException("Missing ClientId when constructing BraintreeGateway");
}
if (ClientSecret == null)
{
throw new ConfigurationException("Missing ClientSecret when constructing BraintreeGateway");
}
if (AccessToken != null)
{
throw new ConfigurationException("AccessToken must not be passed when constructing BraintreeGateway");
}
}