flowOn(Dispatchers.Main) does not change upstream dispatcher

[hoc081098]

    flowOf(1)
      .onEach {
        Timber.d("timer: $it ${Thread.currentThread().name} ${currentCoroutineContext()[ContinuationInterceptor]}")
      }
      .flowOn(Dispatchers.Main)
      .onEach {
        Timber.d("timer [1]: $it ${Thread.currentThread().name} ${currentCoroutineContext()[ContinuationInterceptor]}")
      }
      .launchIn(viewModelScope)

// viewModelScope's context is SupervisorJob() + Dispatchers.Main.immediate

Console

timer: 1 main Dispatchers.Main.immediate
timer [1]: 1 main Dispatchers.Main.immediate

[hoc081098]

I saw Dispatchers.Main == Dispatchers.Main.immediate gives true (because they have the same Handler,

kotlinx.coroutines/ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt

Line 175 in 6dfabf7

override fun equals(other: Any?): Boolean = other is HandlerContext && other.handler === handler

)

So

kotlinx.coroutines/kotlinx-coroutines-core/common/src/flow/internal/ChannelFlow.kt

Line 166 in 6dfabf7

if (newContext == collectContext)

will not change the context.

Is that expected behavior?