Starting with 1.0.0-beta02, trying to set the container color of a TopAppBar to be transparent no longer works.

TopAppBarDefaults.centerAlignedTopAppBarColors(
   containerColor = Color.Transparent
)

It looks like in https://android-review.googlesource.com/c/platform/frameworks/support/+/2189523 the behavior was changed so that there is always a Surface with the default color underneath the TopAppBar, whose color can't be configured to be transparent.