Jenkins 1.637 introduced a problem related to parameterized builds. This problem has impact in multiple situations, as I am going to describe next.

Jenkins 1.637 introduced the "OptionalJobProperty" class. Please see this commit: https://github.com/jenkinsci/jenkins/commit/53c86ec857a49609613ed1871a01830d51a89265

Job configuration

Follow the following steps:

• Create a new job "Job1"
• Activate the option "This build is parameterized"
• Don't add any parameter
• Save the job
• Get back to the job configuration

Previous to this version, you would see that Jenkins was "smart" enough to understand that it makes no sense to have a parameterized job without parameters, so it wouldn't save this option.

After this version, the "This build is parameterized" option is active (and actually saved to the config.xml file) without any parameter. See the attached image "1".

The config.xml file contains the following content.

<properties>
    <hudson.model.ParametersDefinitionProperty/>
  </properties>

Downstream job trigger

Follow these steps:

• Install the "Parameterized Trigger Plugin"
• Add a new job "Job0". Add a downstream job "Job1", and pass the current build parameters.
• Trigger "Job0", and wait for it to trigger "Job1"

Result

• Before Jenkins 1.637, the job is triggered with no problems.
• After Jenkins 1.637, Job1 won't be triggered.
  This appears in Console Output.

ERROR: Failed to build parameters to trigger project: Job1
java.lang.NullPointerException
at hudson.plugins.parameterizedtrigger.ProjectSpecificParameterValuesActionTransform.getParameterDefinitionsMap(ProjectSpecificParameterValuesActionTransform.java:47)
at hudson.plugins.parameterizedtrigger.ProjectSpecificParameterValuesActionTransform.transformParametersAction(ProjectSpecificParameterValuesActionTransform.java:29)
at hudson.plugins.parameterizedtrigger.ProjectSpecificParametersActionFactory.getProjectSpecificBuildActions(ProjectSpecificParametersActionFactory.java:32)
at hudson.plugins.parameterizedtrigger.BuildTriggerConfig.getBuildActions(BuildTriggerConfig.java:290)
at hudson.plugins.parameterizedtrigger.ParameterizedDependency.shouldTriggerBuild(ParameterizedDependency.java:60)
at hudson.tasks.BuildTrigger.execute(BuildTrigger.java:245)
at hudson.model.AbstractBuild$AbstractBuildExecution.cleanUp(AbstractBuild.java:684)
at hudson.model.Build$BuildExecution.cleanUp(Build.java:200)
at hudson.model.Run.execute(Run.java:1785)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Finished: SUCCESS

This is not a major problem because there a workaround.