MapStruct requires Impl class
I have next classes: Mapper public interface DeviceTokensMapper { DeviceTokensMapper INSTANCE = Mappers.getMapper(DeviceTokensMapper.class); @Mappings({ @Mapping(source = "tokenName", target = "tokenName"), @Mapping(source = "userOsType", target = "osType"), }) DeviceTokensDTO toDeviceTokensDTO(DeviceTokens deviceTokens); } Entity: @Entity public class DeviceTokens { @Id @Column(name="token_name", nullable = false) private String tokenName; @Column(name = "os", nullable = false) @Enumerated private UserOSType userOsType; public DeviceTokens() {} public DeviceTokens(String tokenName, UserOSType