Set border color for a chip in Android

With the Material Components Library and the Chip component you can use a custom style:

<com.google.android.material.chip.Chip
    style="@style/Colors_Widget.MaterialComponents.Chip.Choice"
    ..>

or the app:chipStrokeColor, app:chipStrokeWidth, app:chipBackgroundColor, android:textColor attributes in the xml layout:

<com.google.android.material.chip.Chip
    app:chipBackgroundColor="@color/chip_background_color_selector"
    app:chipStrokeColor="@color/color_choice_chip_strokecolor_selector"
    app:chipStrokeWidth="1dp"
    android:textColor="@color/color_choice_chip_text_color"
    ..>

With this style:

  <style name="Colors_Widget.MaterialComponents.Chip.Choice" parent="Widget.MaterialComponents.Chip.Choice">
    <item name="chipBackgroundColor">@color/chip_background_color_selector</item>
    <item name="chipStrokeColor">@color/color_choice_chip_strokecolor_selector</item>
    <item name="chipStrokeWidth">1dp</item>
    <item name="android:textColor">@color/color_choice_chip_text_color</item>
    <item name="checkedIconVisible">true</item>
  </style>

For the border color you can use a selector to manage the different states.
Something like:

<selector xmlns:android="http://schemas.android.com/apk/res/android">

  <item android:color="@color/primaryLightColor" android:state_enabled="true" android:state_selected="true"/>
  <item android:color="@color/primaryLightColor" android:state_enabled="true" android:state_checked="true"/>
  <!-- 87% opacity. -->
  <item android:alpha="0.87" android:color="#C6CCCD" android:state_enabled="true"/>
  <!-- 38% of 87% opacity. -->
  <item android:alpha="0.33" android:color="#C6CCCD"/>

</selector>

I found the answer myself. I need to add chipStrokeColor and chipStrokeWidth attributes to my chip

  <android.support.design.chip.Chip
      android:id="@+id/chip"
      style="@style/Widget.MaterialComponents.Chip.Filter"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      app:chipStrokeColor="#F0F"
      app:chipStrokeWidth="1dp"
      android:text="my chip"
      app:checkedIcon="@drawable/ic_done_green"
      app:chipBackgroundColor="#FFF" />