JobNode getOrCreateJobNode(String jobName, String jobId) {
    String nodeId = JobNode.createJobNameAndId(jobName, jobId);
    return nodes.computeIfAbsent(nodeId, k -> new JobNode(jobName, jobId, config, appDesc, configGenerator));
  }
Get the {@link JobNode}. Create one if it does not exist.
@param jobName name of the job
@param jobId id of the job
@return {@link JobNode} created with {@code jobName} and {@code jobId}
samza-core/src/main/java/org/apache/samza/execution/JobGraph.java