attribute namespace "" or null or both

hi,

looking on some problems that XmlPull API users have reported
i think that it will be beneficial that in case when namespaces are enabled
we allow both empty string ("") and null as namespace when retrieving
value of attribute that has no namespace 

those two would be equivalent: if namespaces are enabled:
  getAttributeValue ("", name)
  getAttributeValue (null, name)
and if namespaces are disabled
  getAttributeValue ("", name) will throw IllegalArgumentException
  getAttributeValue (null, name) works OK

comments?

thanks,

alek