The pad naming syntax is listed, and the following image shows the syntax:
MetaAffixer master input pad should be named sink_master.
MetaAffixer master output pad should be named src_master.
MetaAffixer slave input pad should be named sink_slave_0, sink_slave_1.
MetaAffixer slave output pad should be named src_slave_0, src_slave_1, src_slave_2.