Gelly Scatter-Gather Iteration, In a single superstep, GatherFunction.updateVertex invoked more then once

[曹建华]

Hi:
According to the code comment, in Scatter-Gather Iteration,
Gather.updateVertex is invoked once per vertex per superstep. But in my
programming, i find GatherFunction.updateVertex was invoked more then once,
is it a problem of the code comment, or a bug of Gelly. My flink version is
1.5.3
Does anyone else have the same problem?