set undefined and null values to '' in the beacon
set undefined and null values to '' in the beacon

encodeURIComponent will encode undefined and null values to 'undefined'
and 'null'.  This isn't what we want in the beacon and is
indistinguishable from a string with the same value.  It's better to send
an empty string and let the back end service determine the data type and
range of the parameter

lognormal/boomerang,lognormal/boomerang