veyron.io/veyron/veyron2/vdl/codegen/java: prefix function variable with _ so that it doesn't conflict with method args.
veyron.io/veyron/veyron2/vdl/codegen/java: prefix function variable with _ so that it doesn't conflict with method args.

Change-Id: I851eac7a4029b83426d1657273dc418c83d44dc7

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23