InMemoryUserDetailsManager: consider improving the error message when no PasswordEncoding has been specified

[michaelisvy]

Expected Behavior

For my testing environment, I have specified a user in memory as shown below. Per the documentation, it is not expected to work because there is no password encoding and I did not specify the prefix {noop} in my password.

@Bean
 public InMemoryUserDetailsManager userDetailsService() {
     UserDetails user1 = User.builder()
             .username("user")
             .password("password")
             .roles("USER")
             .build();
     return new InMemoryUserDetailsManager(user1);
 }

It would be great to have an error message such as:

You have entered a password with no PasswordEncoder. If that is your intent, it should be prefixed with `{noop}`

Current Behavior

We currently have this error message:

java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
	at org.springframework.security.crypto.password.DelegatingPasswordEncoder$UnmappedIdPasswordEncoder.matches(DelegatingPasswordEncoder.java:289) ~[spring-security-crypto-6.2.3.jar:6.2.3]

To be honest, it took me a while to figure out what was happening and I'm sure it would help other users if the message could be more specific.

Context

• Spring Boot 3.2.4
• Spring Security 6.2.3

Thanks a lot for the great work!

[bottlerocketjonny]

Hi! Could I work on this issue please? I'm looking for my first contribution and this seems like it could be good to start with. Thanks 😀