Rollback NLog4j to version 2.1.19, version 2.1.21 introduced some deps that  are not available.
Rollback NLog4j to version 2.1.19, version 2.1.21 introduced some deps that 
are not available.

git-svn-id: 9cbfa5ee8120abdba57ef4b867cdb7e761c71338@370425 13f79535-47bb-0310-9956-ffa450edef68

apache/directory-server,darranl/directory-server,lucastheisen/apache-directory-server,drankye/directory-server,darranl/directory-server,lucastheisen/apache-directory-server,drankye/directory-server,apache/directory-server