public void addCostumHeader(String key, String value) {
      customHeader.put(key, value);
    }
the default thrift http client builder. One can extend the ThriftClientBuilder to builder
custom http client, implement features like authentication or
'DoAs'(hbase-examples/thrift/HttpDoAsClient)
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/client/ThriftConnection.java