public static boolean isConnectionException(Throwable e) {
    if (e == null) {
      return false;
    }
    for (Class<? extends Throwable> clazz : CONNECTION_EXCEPTION_TYPES) {
      if (clazz.isAssignableFrom(e.getClass())) {
        return true;
      }
    }
    return false;
  }
Check if the exception is something that indicates that we cannot contact/communicate with the
server.
@param e exception to check
@return true when exception indicates that the client wasn't able to make contact with server
hbase-client/src/main/java/org/apache/hadoop/hbase/exceptions/ClientExceptionsUtil.java