loadUserByUsername overrides nothing in springboot authentication - spring-boot

Question

I am new to microservice. I want to access username(email)and password
from another service which is userregistration service. when I create
a authentication service and try to access email password I am
getting compile time error.
e: E:\Nil Projects\NewMicroService\security-service\src\main\kotlin\com\security\securityservice\service\JwtUserDetailsService.kt: (16, 5): 'loadUserByUsername' overrides nothing
Here is the my codes
jwtuserdetailsservice.kt
package com.security.securityservice.service
import com.security.securityservice.UserRepository
import com.security.securityservice.entity.User
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.security.core.userdetails.UserDetails
import org.springframework.security.core.userdetails.UsernameNotFoundException
import org.springframework.stereotype.Service
#Service
class JwtUserDetailsService {
#Autowired
private lateinit var userDTO:UserRepository
#Throws(Exception::class)
override fun loadUserByUsername(email: String?): UserDetails {
val user: User =userDTO.findUserByEmail(email)
if (userDTO == null){
UsernameNotFoundException("your email id doesn't exist" + email)
}
return org.springframework.security.core.userdetails.User(user.userId.email,user.userId.password,ArrayList())
}
}
Above i define user.userId.email and user.userId.password because I
define userId in my User.kt . this userId comes from
userRegistration-service, this id holds username and password, but I
am not able to access email and password in authentication servicie I
am getting error at this particular point "return
org.springframework.security.core.userdetails.User(user.userId.email,user.userId.password,ArrayList())"
User.kt
package com.security.securityservice.entity
import javax.persistence.Entity
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType
import javax.persistence.Id
#Entity
data class User(
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
val userAuthId:Long=-1,
val otp:Int=0,
val token:String="",
var userId:Long=-1,
)
ResponseTemplate.kt
package com.security.securityservice.VO
import com.security.securityservice.entity.User
data class ResponseTemplate(
val user:User?=null,
val userRegistration: UserRegistration?=null,
)
UserRegistration.kt
package com.security.securityservice.VO
data class UserRegistration(
val userId:Long=-1,
val firstName:String="",
val lastName:String="",
val email:String="",
)

Answer 1

This has nothing to do with microservice instead with simple OOPs programming.
When you say the child class override certain behaviour then it must have one before, which in your case is None. Looking closely at the definition of the class JwtUserDetailsService there is no parent class/neither any interface present hence there is nothing to override. So line
override fun loadUserByUsername(email: String?): UserDetails {
will never compile. I think you should be implementing* the interface here to provide the behaviour UserDetailsService. You see that loadUserByUsername comes from the interface UserDetailsService
Now the code may compile but in order to make authentication work correctly, you have to properly integrate with the authentication manager.