[Devel] null vs. n/a in radius accounting

[Juha Heinanen]

last week i sent a message about "n/a" value versus leaving radius
attribute out if src/dst leg AVP is not defined.  now i noticed that if
extra attribute is bound to an AVP which is not defined, value of the
corresponding radius attribute is "null".

it would be nice if radius attributes correspnding to undefined AVPs
would be dealt in a consistent way in radius attributes.  i don't care
which one.

-- juha