When configuring ldap connector 2.3 that shups with 4.0 (tried 2.2 connector also) i get an exception when midPoint is trying to iterate schema. Looking at the source, root cause is because the apache directory studio API cannot parse opendj schema.
While reading full opendj schema would be welcome, but besides that it is important for the "Read schema" property on the connector to operate. Even if it is set to "False" the connector still tries to read the schema, and fails. So setting the connector to not actually read schema would be good. The exception attached is when readSchema is "False"
As a test, i installed the openidm ldap (community version 18.104.22.168) connector and this one works fine reading schema, probably as it internally uses the opendj native ldap API.
Not being able to read schema is not a show stopper as most of the data fields can be read as plain old strings (with approriate escaping / binary-ascii encoding). Of course in an ideal world (tm) it would also be nice to be able to use the connector and read opendj schema also.