var builder = new DeserializerBuilder();
var deserializer = builder
    .WithTypeInspector(inspector => new DataContractTypeInspector(inspector) {
        DataMemberSerialization = DataMemberSerialization.OptIn,
        // Since custom type inspectors are added after the built-in ones, they cannot pass their results
        // to the built-in ones, e.g. NamingConventionTypeInspector (responsible for the WithNamingConvention
        // method).
        // The naming convention must be assigned here if there is one, not using WithNamingConvention().
        NamingConvention = new UnderscoredNamingConvention(),
        CacheResults = true, // default
        IncludeNonPublicMembers = false // default
    })
    .IgnoreUnmatchedProperties()
    .Build();