I've found this in the source code

// exposed as public
@PublishedApi
internal fun timer(name: String?, daemon: Boolean) = if (name == null) Timer(daemon) else Timer(name, daemon)

docs of published contains:

When applied to a class or a member with internal visibility allows to use it from public inline functions and makes it effectively public.

the question is: since it's internal why should I care about not making breaking changes to the declaration? It's just there for the purpose of chopping up big public inline functions, no? so published internal inline fun is like a private fun in class, right?

Api consumers can effectively call this by calling a public inline function that calls it. Therefore, modifying the declaration can break binary compatibility.

yeah they

technically

call it because the call in a public inline fun is effectively replaced by the code but still it's not like

timer("foo", false)

Why not like? In the generated client code you get exactly

timer("foo", false)

when calling public

timer("foo", ...)

for example.

It won't break source code if you got rid of the function