Just a typo in the code, which is not covered by tests in the Remoting library. In Jenkins core the JNLPLauncherTest fails in CI. Remoting 3.8 has not been integrated into the core, hence there is no impact on Jenkins instances

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shouldInitializeCorrectlyWithDefaults(hudson.remoting.EngineTest) Time elapsed: 0.019 sec <<< ERROR!
java.io.IOException: Cannot find the JAR Cache location
at hudson.remoting.Engine.startEngine(Engine.java:267)
at hudson.remoting.EngineTest.shouldInitializeCorrectlyWithDefaults(EngineTest.java:54)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)

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