title: Xamarin Support Library (CardView) error when Updated to API 23
body: <p>I've just updated to stable Xamarin.Android(5.1.7.12) which supports Android API 23(6.0).</p>
  
  <p>I've updated my TargetFrameworkVersion to v6.0 (API 23) and I've updated all my support libraries to version 23.0.1.1 (latest NuGet Package available at the time). I've already downloaded all needed to compile to to API23(SDK and BuildTools from Android SDK Manager).</p>
  
  <p>When I try to compile this project I get this error:</p>
  
  <p><code>
  ...
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardBackgroundColor" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardCornerRadius" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardElevation" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardMaxElevation" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardUseCompatPadding" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "cardPreventCornerOverlap" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "contentPadding" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "contentPaddingLeft" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "contentPaddingRight" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "contentPaddingTop" has already been defined
  ...\obj\Debug\resourcecache\983D70AD6A5CC1E0AF6E3C8A8BE731EB\res\values\values.xml(10): error APT0000: Attribute "contentPaddingBottom" has already been defined
  </code>
  Since this are all related to CardView, I tried to remove everything related to CardView (including the support package for CardView) and then everything compiled and worked, but I need CardView...</p>
  
  <p>Is there anything else I need to do to support CardView with Support Library 23?</p>
  
  <p>Is this a known issue with CardView (not Xamarin related), or is it a Xamarin's bug? Everything worked fine when I was using version 22.</p>
  
  <p>.</p>
  
  <p>Updated:
  Just to clear my scenario, I'm using Visual Studio 2015, and my project is not Xamarin.Forms, it is using MvvmCross (3.5.1, from NuGet stable version).</p>
  
  <p>I have another project (a compiled, Release/AnyCPU, DLL, NOT a project reference thru VS) which I depend on and which uses Xamarin.Android.Support.v4 and Xamarin.Android.Support.v7.AppCompat, but no reference to CardView. They are just a bunch of custom classes that I reuse in many projects I develop.</p>
  
  <p>I've updated both NuGet packages (v4 and v7 AppCompat) to the same version my project uses (23.0.1.1). They all are using the one and only android_m2repository_r20.zip file (extracted and all).
  I've tried cleaning the solution, deleting bin/obj on ALL project (including the referenced DLL), and deleting %LocalAppData%\Xamarin\Local\Android.Support.*, which downloaded the android_m2repository_r20.zip (133MB), file FOUR times (the fourth is RecyclerView, which I only reference on this project). I don't know why this files are not cached at the same place, since they are exactly the same, but that's not the issue.</p>
  
  <p>I'm also using GooglePlay services (only Base and Analytics, both version 26.0.0.0), Xamarin.Facebook.Android(4.6.0.0), Parse(1.6.0) and OxyPlot(latest alpha). Just to clear thing, this is my packages.config file:
  <code>
      &lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;packages&gt;
        &lt;package id="Microsoft.Bcl" version="1.1.10" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="Microsoft.Bcl.Build" version="1.0.21" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="Microsoft.Net.Http" version="2.2.29" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.CrossCore" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Droid.Fragging" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.MvvmCrossLibraries" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.Color" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.DownloadCache" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.File" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.Json" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.Messenger" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.PictureChooser" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.Visibility" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.HotTuna.Plugin.WebBrowser" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="MvvmCross.PortableSupport" version="3.5.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="Newtonsoft.Json" version="7.0.1" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="OxyPlot.Core" version="2015.1.744-alpha" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="OxyPlot.Mobile" version="2015.1.744-alpha" targetFramework="MonoAndroid50" /&gt;
        &lt;package id="Parse" version="1.6.0" targetFramework="monoandroid5" /&gt;
        &lt;package id="Xamarin.Android.Support.v4" version="23.0.1.1" targetFramework="monoandroid6" /&gt;
        &lt;package id="Xamarin.Android.Support.v7.AppCompat" version="23.0.1.1" targetFramework="monoandroid6" /&gt;
        &lt;package id="Xamarin.Android.Support.v7.CardView" version="23.0.1.1" targetFramework="monoandroid6" /&gt;
        &lt;package id="Xamarin.Android.Support.v7.RecyclerView" version="23.0.1.1" targetFramework="monoandroid6" /&gt;
        &lt;package id="Xamarin.Facebook.Android" version="4.6.0.0" targetFramework="monoandroid51" /&gt;
        &lt;package id="Xamarin.GooglePlayServices.Analytics" version="26.0.0.0" targetFramework="monoandroid51" /&gt;
        &lt;package id="Xamarin.GooglePlayServices.Base" version="26.0.0.0" targetFramework="monoandroid51" /&gt;
      &lt;/packages&gt;
  </code></p>