auth → credentials Relation

File in src/core/auth	Includes file in src/core/credentials
AuthSourceBuilder.cpp	PinCode.hpp
AuthSourceBuilder.cpp	RFIDCard.hpp
AuthSourceBuilder.cpp	RFIDCardPin.hpp
AuthSourceBuilder.hpp	ICredential.hpp
IDoor.hpp	CredentialFwd.hpp
User.cpp	ICredential.hpp
User.hpp	CredentialFwd.hpp
serializers / UserSerializer.cpp	CredentialFwd.hpp
serializers / UserSerializer.cpp	serializers / PolymorphicCredentialSerializer.hpp