batchSize doesnt work for flume avro manager

The flume appender documentation mention about batch size which states that "Specifies the number of events that should be sent as a batch. The default is 1.". The batchSize doesnt work and always defaults to one.
Its noticed that method FlumeAvroManager.send(final BatchEvent events) is never referred by appender.
Kindly let us know what is the correct config for batch size, the provided config is
<Flume name="flume_avro" compress="false" batchSize="5">...