android:textAllCaps="false" not working for TabLayout design Support

UPDATE FOR DESIGN LIBRARY 23.2.0+

The original answer doesn't work with design library 23.2.0 or later. Thanks for @fahmad6 pointed out in comment, in case someone missed that comment, I'll put it here. You need to set both textAllCaps and android:textAllCaps to false to disable all capitalize setting.

<style name="MyCustomTextAppearance" parent="TextAppearance.Design.Tab">
      <item name="textAllCaps">false</item>
      <item name="android:textAllCaps">false</item>
</style>

ORIGINAL ANSWER

By default, tabs are created by TabLayout sets the textAllCaps property to be true, you have to define a style making this flag false.

<style name="MyCustomTabLayout" parent="Widget.Design.TabLayout">
      <item name="tabTextAppearance">@style/MyCustomTextAppearance</item>
</style>

<style name="MyCustomTextAppearance" parent="TextAppearance.Design.Tab">
      <item name="textAllCaps">false</item>
</style>

@Paresh Mayani answer is correct however you can create only tab style

<style name="MyCustomTextAppearance" parent="TextAppearance.Design.Tab">
  <item name="textAllCaps">false</item>
</style>

And use it using

<android.support.design.widget.TabLayout
    app:tabTextAppearance="@style/MyCustomTextAppearance"
    .../>

https://stackoverflow.com/a/34678235/1025379

<android.support.design.widget.TabLayout
    app:tabTextAppearance="@android:style/TextAppearance.Widget.TabWidget"
/>