Looking at https://jenkins.io/doc/pipeline/steps/workflow-cps/#parallel-execute-in-parallel I see:

      parallel: Execute in parallel
      org.kohsuke.stapler.NoStaplerConstructorException: There’s no @DataBoundConstructor on any constructor of class org.jenkinsci.plugins.workflow.cps.steps.ParallelStep
      

      Notice that the description is missing.

          [JENKINS-39605] Documentation for "parallel" step is broken

          cowwoc created issue -
          cowwoc made changes -
          Component/s New: pipeline [ 21692 ]
          Oleg Nenashev made changes -
          Component/s Original: core [ 15593 ]
          Oleg Nenashev made changes -
          Component/s New: workflow-cps-plugin [ 21713 ]
          Marcus Philip made changes -
          Priority Original: Critical [ 2 ] New: Major [ 3 ]
          Jesse Glick made changes -
          Link New: This issue duplicates JENKINS-30572 [ JENKINS-30572 ]
          Jesse Glick made changes -
          Resolution New: Duplicate [ 3 ]
          Status Original: Open [ 1 ] New: Resolved [ 5 ]

            Unassigned Unassigned
            cowwoc cowwoc
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              Created:
              Updated:
              Resolved: