gistfile1.cs

return new Dictionary<string, dynamic>()
{
    {"firstName", firstName},
    {"lastName", lastName},
    {"ssn", ssn},
    {"allEvaluationsPassed", allTestsPassed},
    {"reasons", !allTestsPassed ? failureList : null}
}
 .Where(entry => entry.Value != null)
 .ToDictionary(k => k.Key, v => v.Value);