We try to clone a ssh git repo with managed credentials (ssh username with private key) like

ssh://service@my-server.com:29418/my-project.git

stack-trace:
10:05:13 Cloning the remote Git repository*10:05:16* FATAL: Cannot open session, connection is not authenticated.10:05:16 java.lang.IllegalStateException: Cannot open session, connection is not authenticated.10:05:16 at com.trilead.ssh2.Connection.openSession(Connection.java:1143)10:05:16 at org.jenkinsci.plugins.gitclient.trilead.TrileadSession.exec(TrileadSession.java:32)10:05:16 at org.eclipse.jgit.transport.TransportGitSsh$SshFetchConnection.<init>(TransportGitSsh.java:264)10:05:16 at org.eclipse.jgit.transport.TransportGitSsh.openFetch(TransportGitSsh.java:162)10:05:16 at org.eclipse.jgit.transport.FetchProcess.executeImp(FetchProcess.java:136)10:05:16 at org.eclipse.jgit.transport.FetchProcess.execute(FetchProcess.java:122)10:05:16 at org.eclipse.jgit.transport.Transport.fetch(Transport.java:1201)10:05:16 at org.eclipse.jgit.api.FetchCommand.call(FetchCommand.java:128)10:05:16 at org.jenkinsci.plugins.gitclient.JGitAPIImpl$5.execute(JGitAPIImpl.java:1424)10:05:16 at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:153)10:05:16 at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$1.call(RemoteGitImpl.java:146)10:05:16 at hudson.remoting.UserRequest.perform(UserRequest.java:153)
If we use git.exe it works without problems. Also other jgit implementations (on cmd) are working without problems.

It seems to be related to the latest Jenkins LTS release, where the trilead version was upgraded. 

We have also tried to enable logging for 

com.trilead.level = FINE
org.jenkinsci.plugins.gitclient.trilead.level = FINE
org.eclipse.jgit.level = FINE

but we get only a big content of "NUL" values in the log .. nothing more. 

The certificates and also java versions seem to be ok (latest 141).

The job is a "simple" jenkins maven job (not freestyle, not multibranch and no pipeline stuff).

Git server on the end is gitblit.