Originally raised in spring-projects/spring-boot#17861

The org.springframework.ldap.core.support.AbstractContextSource class has a setupAuthenticatedEnvironment which is passed a principal and credentials. If either of these are null a NullPointerException is thrown because null values are not permitted in a Hashtable.

I think it might be better if DirContextAuthenticationStrategy implementations could guard against null values and not add entries in such cases.