code: public static int getMaxConcurrentRunsForFlow(String projectName, String flowName,
        int defaultMaxConcurrentRuns, Map<Pair<String, String>, Integer> maxConcurrentRunsFlowMap) {
        return maxConcurrentRunsFlowMap.getOrDefault(new Pair(projectName, flowName),
            defaultMaxConcurrentRuns);
    }
docs: Get the maximum number of concurrent runs for the specified flow, using the value in
  azkaban.concurrent.runs.oneflow.whitelist if explictly specified for the flow, and otherwise
  azkaban.max.concurrent.runs.oneflow or the default.
  
  @param projectName project name
  @param flowName flow name
  @param defaultMaxConcurrentRuns default max number of concurrent runs for one flow, if not
  explcitly specified for the flow.
  @param maxConcurrentRunsFlowMap map of (project, flow) to max number of concurrent runs for
  flow for which the value is explicitly specified via whitelist.
  @return the maximum number of concurrent runs for the flow.