Use the correct field to check if it's nil

[jiho-jung]

I found that an incorrect field is used to check if it's nil. See below

if a.rangeProtoMin != nil {
   binary.BigEndian.PutUint16(data[n:], *a.rangeProtoMax)
   n += 2
}

It would be like this. If I am correct, please apply my changes.

if a.rangeProtoMax != nil {
   binary.BigEndian.PutUint16(data[n:], *a.rangeProtoMax)
   n += 2
}

libOpenflow/openflow15/nx_action.go

Line 732 in f8e71bf

if a.RangeProtoMin != nil {

libOpenflow/openflow13/nx_action.go

Line 715 in f8e71bf

if a.rangeProtoMin != nil {