InetOrgPerson uid should not be a mandatory field - may cause regression as of version 7.1.0

Describe the bug

1. CTOR org.springframework.security.ldap.userdetails.InetOrgPerson.Essence.Essence(DirContextOperations) with attribute "uid" null, throws IllegalArgumentException with "uid cannot be null".
2. org.springframework.security.ldap.userdetails.InetOrgPerson.getUid() while uid is null throws NullPointerException with "uid cannot be null".

The source code contradicts itself in these lines

	private @Nullable String uid;

	public String getUid() {
		return Objects.requireNonNull(this.uid, "uid cannot be null");
	}

Came with this commit:
https://github.com/spring-projects/spring-security/commit/c5632ccd838fcb2753a978918561081cff037510

To Reproduce
divert from https://github.com/spring-projects/spring-security/blob/ed7ae7969ed2452e6ab76c505bdc6afb9bb957ac/ldap/src/test/java/org/springframework/security/ldap/userdetails/InetOrgPersonTests.java#L120 with uid null

Expected behavior
"uid" should be nullable throughout (to my knowledge and according to LDAP Schema, it's not a mandatory field).
To my knowledge, this was also the behaviour before 7.1.0

Start with org.springframework.security.ldap.userdetails.InetOrgPerson.Essence and InetOrgPerson.getUid(), then inspect ldap/src/test/java/org/springframework/security/ldap/userdetails/InetOrgPersonTests.java around the referenced test. Reproduce the case with a null uid and verify that construction and uid access remain nullable without the reported exceptions.