Basic Auth allowing users to pass through without credentails - spring

Question

I have written a Spring Security Class. But somehow it is not working as expected. I am trying to hit the Rest APIs via a Postman by selecting the Basic Auth method. And here is the scenario.
Correct username and password --> Works (I get 200 responses)
Incorrect username/password --> Works (I get 401 responses)
Select No Auth in Postman --> Doesn't Work (I should get 401, but it allows the request to pass through)
Now for #1 and #2 it works fine. Its the #3 that is the troublesome part. My Security code is written like:
#Configuration
#EnableWebSecurity
class SecurityConfig {
#Value("\${spring.security.user.name}")
private val userName : String? = null
#Value("\${spring.user.password}")
private val password : String? = null
#Autowired
lateinit var appAuthenticationEntryPoint: AppAuthenticationEntryPoint
#Bean
fun passwordEncoder(): PasswordEncoder {
return MyPasswordDelegation().createDelegatingPasswordEncoder()
}
#Bean
#Throws(Exception::class)
fun userDetailsService(): InMemoryUserDetailsManager? {
val userDetails : UserDetails = User.withUsername(userName).password(passwordEncoder().encode(password)).roles("USER").build()
return InMemoryUserDetailsManager(userDetails)
}
#Throws(Exception::class)
#Bean
fun filterChain(httpSecurity : HttpSecurity): SecurityFilterChain {
httpSecurity.csrf().disable()
// Allow only HTTPS Requests
httpSecurity.requiresChannel {
channel -> channel.anyRequest().requiresSecure()
}.authorizeRequests {
authorize -> authorize.antMatchers("/app-download/**").fullyAuthenticated()
.and()
.httpBasic()
.and()
.exceptionHandling()
.authenticationEntryPoint(myAuthenticationEntryPoint)
}
return httpSecurity.build()
}
}
Can you please tell me what am I doing wrong here?