# SplitPairRule.Builder
# SplitPairRule.Builder
Artifact: [androidx.window:window](https://developer.android.com/jetpack/androidx/releases/window)
[View Source](https://cs.android.com/search?q=file:androidx/window/embedding/SplitPairRule.kt+class:androidx.window.embedding.SplitPairRule.Builder)
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
*** ** * ** ***
Kotlin \|[Java](https://developer.android.com/reference/androidx/window/embedding/SplitPairRule.Builder "View this page in Java")
```
class SplitPairRule.Builder
```
*** ** * ** ***
Builder for [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule).
## Summary
| ### Public constructors |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#Builder(kotlin.collections.Set))`(filters: `[Set](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-set/index.html)`<`[SplitPairFilter](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairFilter)`>)` |
| ### Public functions |
|-------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule) | [build](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#build())`()` Builds a `SplitPairRule` instance. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setClearTop](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setClearTop(kotlin.Boolean))`(clearTop: `[Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html)`)` Sets whether the existing secondary container on top and all activities in it should be destroyed when a new split is created using this rule. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setDefaultSplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setDefaultSplitAttributes(androidx.window.embedding.SplitAttributes))`(defaultSplitAttributes: `[SplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes)`)` Sets the default [SplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes) to apply on the activity containers pair when the host task bounds satisfy [minWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minWidthDp()), [minHeightDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minHeightDp()), [minSmallestWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minSmallestWidthDp()), [maxAspectRatioInPortrait](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#maxAspectRatioInPortrait()) and [maxAspectRatioInLandscape](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#maxAspectRatioInLandscape()) requirements. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setFinishPrimaryWithSecondary](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setFinishPrimaryWithSecondary(androidx.window.embedding.SplitRule.FinishBehavior))`(` ` finishPrimaryWithSecondary: `[SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) `)` Sets the behavior of the primary container when all activities are finished in the associated secondary container. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setFinishSecondaryWithPrimary](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setFinishSecondaryWithPrimary(androidx.window.embedding.SplitRule.FinishBehavior))`(` ` finishSecondaryWithPrimary: `[SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) `)` Sets the behavior of the secondary container when all activities are finished in the associated primary container. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setMaxAspectRatioInLandscape](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setMaxAspectRatioInLandscape(androidx.window.embedding.EmbeddingAspectRatio))`(aspectRatio: `[EmbeddingAspectRatio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio)`)` Sets the largest value of the aspect ratio, expressed as `width / height` in decimal form, of the parent window bounds in landscape when the split should be used. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setMaxAspectRatioInPortrait](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setMaxAspectRatioInPortrait(androidx.window.embedding.EmbeddingAspectRatio))`(aspectRatio: `[EmbeddingAspectRatio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio)`)` Sets the largest value of the aspect ratio, expressed as `height / width` in decimal form, of the parent window bounds in portrait when the split should be used. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setMinHeightDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setMinHeightDp(kotlin.Int))`(minHeightDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Sets the smallest value of height of the parent task window when the split should be used, in DP. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setMinSmallestWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setMinSmallestWidthDp(kotlin.Int))`(minSmallestWidthDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Sets the smallest value of the smallest possible width of the parent window in any rotation when the split should be used, in DP. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setMinWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setMinWidthDp(kotlin.Int))`(minWidthDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)` Sets the smallest value of width of the parent window when the split should be used, in DP. |
| [SplitPairRule.Builder](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder) | [setTag](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#setTag(kotlin.String))`(tag: `[String](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-string/index.html)`?)` Sets a unique string to identify this [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule), which defaults to `null`. |
## Public constructors
### Builder
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
Builder(filters: Set)
```
| Parameters |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------|
| `filters: `[Set](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-set/index.html)`<`[SplitPairFilter](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairFilter)`>` | Filters used to choose when to apply this rule. The rule may be used if any one of the provided filters matches. |
## Public functions
### build
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun build(): SplitPairRule
```
Builds a `SplitPairRule` instance.
| Returns |
|---------------------------------------------------------------------------------------------------------|-----------------------------------|
| [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule) | The new `SplitPairRule` instance. |
### setClearTop
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setClearTop(clearTop: Boolean): SplitPairRule.Builder
```
Sets whether the existing secondary container on top and all activities in it should be destroyed when a new split is created using this rule. Otherwise the new secondary will appear on top by default.
| Parameters |
|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------|
| `clearTop: `[Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html) | whether the existing secondary container on top and all activities in it should be destroyed when a new split is created using this rule. |
### setDefaultSplitAttributes
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setDefaultSplitAttributes(defaultSplitAttributes: SplitAttributes): SplitPairRule.Builder
```
Sets the default [SplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes) to apply on the activity containers pair when the host task bounds satisfy [minWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minWidthDp()), [minHeightDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minHeightDp()), [minSmallestWidthDp](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#minSmallestWidthDp()), [maxAspectRatioInPortrait](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#maxAspectRatioInPortrait()) and [maxAspectRatioInLandscape](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule.Builder#maxAspectRatioInLandscape()) requirements.
| Parameters |
|---------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `defaultSplitAttributes: `[SplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes) | the default [SplitAttributes](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes) to apply on the activity containers pair when the host task bounds satisfy all the rule requirements. |
### setFinishPrimaryWithSecondary
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setFinishPrimaryWithSecondary(
finishPrimaryWithSecondary: SplitRule.FinishBehavior
): SplitPairRule.Builder
```
Sets the behavior of the primary container when all activities are finished in the associated secondary container.
| Parameters |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `finishPrimaryWithSecondary: `[SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) | the [SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) of the primary container when all activities are finished in the associated secondary container. |
| See also |
|--------------------------------------------------------------------------------------------------------------------------|---|
| [NEVER](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#NEVER()) | |
| [ALWAYS](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#ALWAYS()) | |
| [ADJACENT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#ADJACENT()) | |
### setFinishSecondaryWithPrimary
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setFinishSecondaryWithPrimary(
finishSecondaryWithPrimary: SplitRule.FinishBehavior
): SplitPairRule.Builder
```
Sets the behavior of the secondary container when all activities are finished in the associated primary container.
| Parameters |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `finishSecondaryWithPrimary: `[SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) | the [SplitRule.FinishBehavior](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior) of the secondary container when all activities are finished in the associated primary container. |
| See also |
|--------------------------------------------------------------------------------------------------------------------------|---|
| [NEVER](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#NEVER()) | |
| [ALWAYS](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#ALWAYS()) | |
| [ADJACENT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule.FinishBehavior#ADJACENT()) | |
### setMaxAspectRatioInLandscape
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setMaxAspectRatioInLandscape(aspectRatio: EmbeddingAspectRatio): SplitPairRule.Builder
```
Sets the largest value of the aspect ratio, expressed as `width / height` in decimal form, of the parent window bounds in landscape when the split should be used. When the window aspect ratio is greater than requested here, activities in the secondary container will be stacked on top of the activities in the primary one, completely overlapping them.
This value is only used when the parent window is in landscape (width height).
The default is [SPLIT_MAX_ASPECT_RATIO_LANDSCAPE_DEFAULT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MAX_ASPECT_RATIO_LANDSCAPE_DEFAULT()) if the app doesn't set, which is the recommend value to always allow split when the parent window is in landscape.
| Parameters |
|--------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `aspectRatio: `[EmbeddingAspectRatio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio) | the largest value of the aspect ratio, expressed as `width / height` in decimal form, of the parent window bounds in landscape when the split should be used. |
| See also |
|------------------------------------------------------------------------------------------------------------------------------------|---|
| [ratio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ratio(kotlin.Float)) | |
| [ALWAYS_ALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ALWAYS_ALLOW()) | |
| [ALWAYS_DISALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ALWAYS_DISALLOW()) | |
### setMaxAspectRatioInPortrait
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setMaxAspectRatioInPortrait(aspectRatio: EmbeddingAspectRatio): SplitPairRule.Builder
```
Sets the largest value of the aspect ratio, expressed as `height / width` in decimal form, of the parent window bounds in portrait when the split should be used. When the window aspect ratio is greater than requested here, activities in the secondary container will be stacked on top of the activities in the primary one, completely overlapping them.
This value is only used when the parent window is in portrait (height \>= width).
The default is [SPLIT_MAX_ASPECT_RATIO_PORTRAIT_DEFAULT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MAX_ASPECT_RATIO_PORTRAIT_DEFAULT()) if the app doesn't set, which is the recommend value to only allow split when the parent window is not too stretched in portrait.
| Parameters |
|--------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `aspectRatio: `[EmbeddingAspectRatio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio) | the largest value of the aspect ratio, expressed as `height / width` in decimal form, of the parent window bounds in portrait when the split should be used. |
| See also |
|------------------------------------------------------------------------------------------------------------------------------------|---|
| [ratio](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ratio(kotlin.Float)) | |
| [ALWAYS_ALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ALWAYS_ALLOW()) | |
| [ALWAYS_DISALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/EmbeddingAspectRatio#ALWAYS_DISALLOW()) | |
### setMinHeightDp
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setMinHeightDp(minHeightDp: @IntRange(from = 0) Int): SplitPairRule.Builder
```
Sets the smallest value of height of the parent task window when the split should be used, in DP. When the window size is smaller than requested here, activities in the secondary container will be stacked on top of the activities in the primary one, completely overlapping them.
It is useful if it's necessary to split the parent window horizontally for this [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule).
The default is [SPLIT_MIN_DIMENSION_DP_DEFAULT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_DP_DEFAULT()) if the app doesn't set. [SPLIT_MIN_DIMENSION_ALWAYS_ALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_ALWAYS_ALLOW()) means to always allow split.
| Parameters |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------|
| `minHeightDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | the smallest value of height of the parent task window when the split should be used, in DP. |
| See also |
|-------------------------------------------------------------------------------------------------------------------------------------------|---|
| [TOP_TO_BOTTOM](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes.LayoutDirection#TOP_TO_BOTTOM()) | |
| [BOTTOM_TO_TOP](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributes.LayoutDirection#BOTTOM_TO_TOP()) | |
### setMinSmallestWidthDp
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setMinSmallestWidthDp(minSmallestWidthDp: @IntRange(from = 0) Int): SplitPairRule.Builder
```
Sets the smallest value of the smallest possible width of the parent window in any rotation when the split should be used, in DP. When the window size is smaller than requested here, activities in the secondary container will be stacked on top of the activities in the primary one, completely overlapping them.
The default is [SPLIT_MIN_DIMENSION_DP_DEFAULT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_DP_DEFAULT()) if the app doesn't set. [SPLIT_MIN_DIMENSION_ALWAYS_ALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_ALWAYS_ALLOW()) means to always allow split.
| Parameters |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------|
| `minSmallestWidthDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | the smallest value of the smallest possible width of the parent window in any rotation when the split should be used, in DP. |
### setMinWidthDp
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setMinWidthDp(minWidthDp: @IntRange(from = 0) Int): SplitPairRule.Builder
```
Sets the smallest value of width of the parent window when the split should be used, in DP. When the window size is smaller than requested here, activities in the secondary container will be stacked on top of the activities in the primary one, completely overlapping them.
The default is [SPLIT_MIN_DIMENSION_DP_DEFAULT](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_DP_DEFAULT()) if the app doesn't set. [SPLIT_MIN_DIMENSION_ALWAYS_ALLOW](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitRule#SPLIT_MIN_DIMENSION_ALWAYS_ALLOW()) means to always allow split.
| Parameters |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------|
| `minWidthDp: @`[IntRange](https://developer.android.com/reference/kotlin/androidx/annotation/IntRange)`(from = 0) `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | the smallest value of width of the parent window when the split should be used, in DP. |
### setTag
Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/window#1.1.0)
```
fun setTag(tag: String?): SplitPairRule.Builder
```
Sets a unique string to identify this [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule), which defaults to `null`. The suggested usage is to set the tag to be able to differentiate between different rules in the [SplitAttributesCalculatorParams.splitRuleTag](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitAttributesCalculatorParams#splitRuleTag()).
| Parameters |
|---------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------|
| `tag: `[String](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-string/index.html)`?` | unique string to identify this [SplitPairRule](https://developer.android.com/reference/kotlin/androidx/window/embedding/SplitPairRule). |