docs: static MapKeyLoader.Role assignRole(boolean isPartitionOwner, boolean isMapNamePartition,
                                          boolean isMapNamePartitionFirstReplica) {
          if (isMapNamePartition) {
              if (isPartitionOwner) {
                  // map-name partition owner is the SENDER
                  return MapKeyLoader.Role.SENDER;
              } else {
                  if (isMapNamePartitionFirstReplica) {
                      // first replica of the map-name partition is the SENDER_BACKUP
                      return MapKeyLoader.Role.SENDER_BACKUP;
                  } else {
                      // other replicas of the map-name partition do not have a role
                      return MapKeyLoader.Role.NONE;
                  }
              }
          } else {
              // ordinary partition owners are RECEIVERs, otherwise no role
              return isPartitionOwner ? MapKeyLoader.Role.RECEIVER : MapKeyLoader.Role.NONE;
          }
      }