IssueTracker

The interesting part that not everything in this class is a constant

object Button {
    private val ButtonHorizontalPadding = 16.dp
    private val ButtonVerticalPadding = 8.dp

    /**
     * The default inner padding used by [Button]
     */
    val DefaultInnerPadding = InnerPadding(
        start = ButtonHorizontalPadding,
        top = ButtonVerticalPadding,
        end = ButtonHorizontalPadding,
        bottom = ButtonVerticalPadding
    )

    /**
     * The default min width applied for the [Button].
     * Note that you can override it by applying [Modifier.widthIn] directly on [Button].
     */
    val DefaultMinWidth = 64.dp

    /**
     * The default min width applied for the [Button].
     * Note that you can override it by applying [Modifier.heightIn] directly on [Button].
     */
    val DefaultMinHeight = 36.dp

    /**
     * The default disabled background color used by Contained [Button]s
     */
    @Composable
    val defaultDisabledBackgroundColor
        get(): Color = with(MaterialTheme.colors) {
            // we have to composite it over surface here as if we provide a transparent background for
            // Surface and non-zero elevation the artifacts from casting the shadow will be visible
            // below the background.
            onSurface.copy(alpha = 0.12f).compositeOver(surface)
        }

    /**
     * The default disabled content color used by all types of [Button]s
     */
    @Composable
    val defaultDisabledContentColor
        get(): Color = with(MaterialTheme.colors) {
            EmphasisAmbient.current.disabled.applyEmphasis(onSurface)
        }
}

I am not sure the composable getters should be placed in a file with such name.
in the same way this would be a mistake to rename this class to FooConstrants

object Scaffold {
    /**
     * The possible positions for a [FloatingActionButton] attached to a [Scaffold].
     */
    enum class FabPosition {
        /**
         * Position FAB at the bottom of the screen in the center, above the [BottomAppBar] (if it
         * exists)
         */
        Center,
        /**
         * Position FAB at the bottom of the screen at the end, above the [BottomAppBar] (if it
         * exists)
         */
        End
    }
}

and what about this use case, it was about namespacing, not defining constants:
object TabRow {
    /**
     * Data class that contains information about a tab's position on screen
     *
     * @property left the left edge's x position from the start of the [TabRow]
     * @property right the right edge's x position from the start of the [TabRow]
     * @property width the width of this tab
     */
    @Immutable
    data class TabPosition internal constructor(val left: Dp, val width: Dp) {
        val right: Dp get() = left + width
    }

    /**
     * Positions and animates the given [indicator] between tabs when [selectedIndex] changes.
     */
    @Composable
    fun IndicatorContainer(
        tabPositions: List<TabPosition>,
        selectedIndex: Int,
        indicator: @Composable () -> Unit
    ) {
       ...
    }
}