Inline functions require Kotlin compiler at least 1.3.50 if they were
generated by the compiler with API version >= 1.4. This is because since
API version 1.4, we've changed the generation scheme of parameter
nullability assertions and they now refer to methods from the standard
library which did not exist until 1.4. See
JvmSerializerExtension.writeInlineParameterNullCheckRequirement.