protected static Throwable unwrap(Throwable t) {
    if (t == null) {
      return t;
    }
    if (t instanceof TIOError || t instanceof IOError) {
      t = t.getCause();
    }
    return ClientExceptionsUtil.findException(t);
  }
Keep some metrics for commonly seen exceptions Try and put the most common types first. Place
child types before the parent type that they extend. If this gets much larger we might have
to go to a hashmap
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift/ThriftMetrics.java