NumberFormatException when calling refreshObject

Hi!
Sometimes I'm getting a NumberFormatException (null) when calling TopoApi.refreshObject(). Why is that and what goes wrong?

Here's the stack trace:

java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:415)
at java.lang.Integer.parseInt(Integer.java:497)
at com.adventnet.nms.topodb.SetupNode.addSNMPInterface(SetupNode.java:985)
at com.adventnet.nms.topodb.SetupNode.performV3Discovery(SetupNode.java:709)
at com.adventnet.nms.topodb.SetupNode.pingAddress(SetupNode.java:3677)
at com.adventnet.nms.topodb.SetupNode.update(SetupNode.java:3905)
at com.adventnet.nms.topodb.TopoDB.refreshObject(TopoDB.java:4846

Thanks in advance!

Regards,
Henrik