protected static Quotas quotasFromData(final byte[] data, int offset, int length)
    throws IOException {
    int magicLen = ProtobufMagic.lengthOfPBMagic();
    if (!ProtobufMagic.isPBMagicPrefix(data, offset, magicLen)) {
      throw new IOException("Missing pb magic prefix");
    }
    return Quotas.parseFrom(new ByteArrayInputStream(data, offset + magicLen, length - magicLen));
  }
Returns the current space quota snapshot of the given {@code tableName} from
{@code QuotaTableUtil.QUOTA_TABLE_NAME} or null if the no quota information is available for
that tableName.
@param conn      connection to re-use
@param tableName name of the table whose current snapshot is to be retreived
hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaTableUtil.java