code: protected void initBroadcastInputsSerializers(int numBroadcastInputs) throws Exception {
  		this.broadcastInputSerializers = new TypeSerializerFactory<?>[numBroadcastInputs];
  
  		ClassLoader userCodeClassLoader = getUserCodeClassLoader();
  
  		for (int i = 0; i < numBroadcastInputs; i++) {
  			//  ---------------- create the serializer first ---------------------
  			final TypeSerializerFactory<?> serializerFactory = this.config.getBroadcastInputSerializer(i, userCodeClassLoader);
  			this.broadcastInputSerializers[i] = serializerFactory;
  		}
  	}
docs: Creates all the serializers and iterators for the broadcast inputs.