This will be used in the compiler starting from 1.5.20 instead of the
currently used approach of looking for the single value parameter of the
primary constructor. The problem with the current approach is that
primary constructor can be private (since 1.4.30) and the property could
always be private. Relying on private declarations from metadata is
dangerous; for example lazy IR doesn't usually create stubs for private
declarations, and it didn't create stubs for private inline class
constructors before b5f9b1df, which led to the problem reported in
KT-44723.