Add check if the sequence is optional, if it is not persent encode null 0x80 and false in the presence map.

Author: martinfantini

src/mfast/coder/encoder_v2/fast_encoder_core.h

@@ -265,7 +265,7 @@ inline void fast_encoder_core::encode_field(const T &ext_ref,
       this->current_->set_next_bit(false);
     if(!std::is_same<typename T::length_type::operator_category, constant_operator_tag>::value &&
        !std::is_same<typename T::length_type::operator_category, copy_operator_tag>::value &&
-       !std::is_same<typename T::length_type::operator_category, default_operator_tag>::value )
+       !std::is_same<typename T::length_type::operator_category, default_operator_tag>::value)
       strm_.encode_null();
     return;
   }