The 'parameters' for
[SBObject sendEvent:id:parameters:] is a variadic argument list that contains four character codes and IDs (as pairs) and is terminated by a four-character-code with value 0.
fourcc1, id1, fourcc2, id2, ..., fourccN, idN, 0
The metadata has a way to describe a NUL terminated argument list for a variadic method, but that only works when (1) all elements of the list have the same C type, and (2) that C type is "id".
The last bit is fairly easy to fix, but (1) requires an update to the metadata structure.