As well as breaking hybrid plugin installation (again) with the 19.2 update, Adobe have also broken the NewSymbolPattern function in the AISymbolSuite.
This function has been around since CS3 and has always had the same first two arguments which are described in the header as below for CS3 right to the latest CC 2015 19.2 SDK:
/** Creates a new symbol definition from specified source art, which is copied as
the defining art for the new symbol.
@param newSymbolPattern [out] A buffer in which to return the new symbol reference.
@param definitionArt The source art, or \c NULL to create a symbol whose definition
is an empty group.
With 19.2, if you pass NULL as the second argument (definitionArt), you get a PARM error, even though the header says this should create a symbol whose definition is an empty group. Passing NULL works with previous versions.