private TransitRegionStateProcedure[]
    createAssignProcedures(Map<ServerName, List<RegionInfo>> assignments) {
    return assignments.entrySet().stream()
      .flatMap(e -> e.getValue().stream().map(hri -> regionStates.getOrCreateRegionStateNode(hri))
        .map(regionNode -> createAssignProcedure(regionNode, e.getKey())))
      .sorted(AssignmentManager::compare).toArray(TransitRegionStateProcedure[]::new);
  }
Tied to {@link #createAssignProcedures(List)} in that it is called if caller is unable to run
this method. Presumes all Regions are in appropriate state ripe for assign; no checking of
Region state is done in here.
@param assignments Map of assignments from which we produce an array of AssignProcedures.
@return Assignments made from the passed in <code>assignments</code>
@see #createAssignProcedures(List)
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java