private String getOnlineRegionsAsPrintableString() {
    StringBuilder sb = new StringBuilder();
    for (Region r : this.onlineRegions.values()) {
      if (sb.length() > 0) {
        sb.append(", ");
      }
      sb.append(r.getRegionInfo().getEncodedName());
    }
    return sb.toString();
  }
Converts a pair of {@link RegionInfo} and {@code long} into a {@link RegionSpaceUse} protobuf
message.
@param regionInfo  The RegionInfo
@param sizeInBytes The size in bytes of the Region
@return The protocol buffer
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java