The actual issue is that JNLPLauncher's workDirSettings is declared @Nonnull https://github.com/jenkinsci/jenkins/blob/393680beb5d64628bdf8d9e5bf8daf4cab2191ad/core/src/main/java/hudson/slaves/JNLPLauncher.java#L69-L77  while it's actually nullable, as a default value can be safely computed (as done by deprecated constructor)

also read https://github.com/jenkinsci/jep/pull/111

Yep, I am going to remove the non-null requirement

Created https://github.com/jenkinsci/jenkins/pull/3463
IMHO it deserves backporting

Code changed in jenkins
User: Oleg Nenashev
Path:
core/src/main/java/hudson/slaves/JNLPLauncher.java
http://jenkins-ci.org/commit/jenkins/229ed44a535034e045005bca942ed04a3093c91c
Log:
JENKINS-51603 - Relax workDirectory requirements for a JNLPLauncher constructor

Code changed in jenkins
User: Oleg Nenashev
Path:
core/src/main/java/hudson/slaves/JNLPLauncher.java
http://jenkins-ci.org/commit/jenkins/d79c6afd2163a30b549314c7c1185bf8bd1fd149
Log:
JENKINS-51603 - Use CheckForNull instead of Nullable

Compare: https://github.com/jenkinsci/jenkins/compare/e4a3138ce5de...d79c6afd2163
*NOTE:* This service been marked for deprecation: https://developer.github.com/changes/2018-04-25-github-services-deprecation/

Functionality will be removed from GitHub.com on January 31st, 2019.

Merged, so fixed, yes?

…though I disagree with the fix.

Code changed in jenkins
User: Jesse Glick
Path:
core/src/main/java/hudson/slaves/JNLPLauncher.java
test/src/test/java/hudson/slaves/JNLPLauncherTest.java
http://jenkins-ci.org/commit/jenkins/98b37699152595f35fce7387be0ee1717596650d
Log:
JENKINS-51603 The proper way to make a parameter optional is to use @DataBoundSetter.

*NOTE:* This service been marked for deprecation: https://developer.github.com/changes/2018-04-25-github-services-deprecation/

Functionality will be removed from GitHub.com on January 31st, 2019.

oleg_nenashev,jglick, I prefer to either backport both the patches or none. Given Jesse's amendment is not yet merged, I lean towards skipping this in 1.121.2.

My amendment is merged, but very recently. I agree that this does not need to be in 2.121.2.