When Catlight tries to send "GET https://my-jenkins:11001/jenkins/api/json?tree=jobs[name,displayName,url,buildable,jobs[name,displayName,url..." at the very begining of configuring a Jenkins connection, Jenkins reponds with 400 saying complaining about Invalid Characters in request. It seems that Catlight does not escape the query parameter "tree" properly. By issuing the same request manually with the query parameter encoded properly Jenkins responds with 200 and correct payload.
The extract from NetworkLog:
2020-02-18 14:41:02.7613 | TRACE | NetworkLog | 76 | ========================================= GET https://my-jenkins:11001/jenkins/api/json?tree=jobs[name,displayName,url,buildable,jobs[name,displayName,url,buildable,jobs[name,displayName,url,buildable,jobs[name,displayName,url,buildable,jobs[name,displayName,url,buildable,jobs[name,displayName,url,buildable]]]]]] User-Agent : Catlight/2.29.1 Accept : application/json Authorization : *****
400 BadRequest Connection : close Date : Tue, 18 Feb 2020 14:41:02 GMT <!doctype html><html lang="de"><head><title>HTTP Status 400