Some Metadata.xml fixes for binding ADTECH Mobile (http://www.adtech.com/) in Xamarin.Android

Metadata.xml

  <!-- This is an example of http://developer.xamarin.com/guides/android/advanced_topics/java_integration_overview/binding-a-java-library/troubleshooting-bindings/#Problem_Duplicate_custom_EventArgs_types

       In this particular case, the conflicting definition is in
       `Com.Adtech.Mobilesdk.Publisher.Vast.Player.ILinearAdPlayer`.
       That interface also defines an "onError" method.

       Error CS0102: The type
       `Com.Adtech.Mobilesdk.Publisher.Vast.Player.ErrorEventArgs'
       already contains a definition for `p0' -->
  <attr path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.player']/interface[@name='VideoPlayerListener']/method[@name='onError' and count(parameter)=1 and parameter[1][@type='java.lang.Exception']]" name="argsType">VideoPlayerListenerOnErrorArgs</attr>


  <!-- The automatically generated event handlers cause some trouble
       here because there are three overloads of `onInvalidAdHandler`.
       We can rename each overload to have a unique name. That way the
       generated event handlers and EventArgs types will have different
       names too, and there won't be any conflicts.

       Error CS0102: The type
       `Com.Adtech.Mobilesdk.Publisher.Vast.Reporting.IInvalidAdListenerImplementor'
       already contains a definition for `OnInvalidAdHandler' -->

  <attr path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.reporting']/interface[@name='InvalidAdListener']/method[@name='onInvalidAd' and count(parameter)=2 and parameter[1][@type='com.adtech.mobilesdk.publisher.vast.model.InLine'] and parameter[2][@type='com.adtech.mobilesdk.publisher.vast.reporting.VastErrorType']]" name="managedName">InvalidAdListenerOnInvalidAdInline</attr>
  <attr path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.reporting']/interface[@name='InvalidAdListener']/method[@name='onInvalidAd' and count(parameter)=2 and parameter[1][@type='com.adtech.mobilesdk.publisher.vast.model.VastResponse'] and parameter[2][@type='com.adtech.mobilesdk.publisher.vast.reporting.VastErrorType']]" name="managedName">InvalidAdListenerOnInvalidAdVastResponse</attr>
  <attr path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.reporting']/interface[@name='InvalidAdListener']/method[@name='onInvalidAd' and count(parameter)=4 and parameter[1][@type='com.adtech.mobilesdk.publisher.vast.model.InLine'] and parameter[2][@type='com.adtech.mobilesdk.publisher.vast.reporting.VastErrorType'] and parameter[3][@type='java.lang.Integer'] and parameter[4][@type='com.adtech.mobilesdk.publisher.vast.model.creatives.MediaFile']]"  name="managedName">InvalidAdListeneronInvalidAdInlineFour</attr>


  <!-- For some reason these interfaces are not accessible, even though
       they seem to be marked "public." Even Java Android apps cannot
       access them. I am not certain what this means or how it is
       possible. But in any case it seems unlikely that these types need
       bindings (considering that they aren't even usable directly in
       Java), so the simplest solution is probably just to remove them.



       ### Additional details for reference

       `javap` shows that interfaces do exist and are public: 

       ```
       $ javap -classpath adtech-mobile-sdk.jar com.adtech.mobilesdk.publisher.vast.player.AdPlayer.AdPodListener
       Compiled from "AdPlayer.java"
       public interface com.adtech.mobilesdk.publisher.vast.player.AdPlayer$AdPodListener {
         public abstract void onAdPodStarted(com.adtech.mobilesdk.publisher.vast.AdType, com.adtech.mobilesdk.publisher.vast.model.AdGroup, int);
         public abstract void onAdPodStopped(com.adtech.mobilesdk.publisher.vast.AdType, com.adtech.mobilesdk.publisher.vast.model.AdGroup);
         public abstract void onAdPodProgress(com.adtech.mobilesdk.publisher.vast.AdType, com.adtech.mobilesdk.publisher.vast.model.AdGroup, int, int);
       }
       ```


       But strangely the `javap` output for the parent class does _not_
       show these types:

       ```
       $ javap -classpath adtech-mobile-sdk.jar -p com.adtech.mobilesdk.publisher.vast.player.AdPlayer | grep AdPodListener || echo "Not found"
       Not found
       ```


       ### Error Messages

       These error messages only appear when you try to build an app
       that references the binding project. They are Java build errors
       rather than C# build errors.

       AdPlayer_AdPodListenerImplementor.java:8: error: cannot find symbol
               com.adtech.mobilesdk.publisher.vast.player.AdPlayer.AdPodListener
                                                                  ^
       symbol:   class AdPodListener
       location: class AdPlayer

       AdPlayer_AdPodPlayerListenerImplementor.java(54,54): Error:  error: cannot find symbol
               com.adtech.mobilesdk.publisher.vast.player.AdPlayer.AdPodPlayerListener
                                                                  ^
       symbol:   class AdPodPlayerListener
       location: class AdPlayer

       AdPlayer_LandingPageListenerImplementor.java(54,54): Error:  error: cannot find symbol
               com.adtech.mobilesdk.publisher.vast.player.AdPlayer.LandingPageListener
                                                                  ^
       symbol:   class LandingPageListener
       location: class AdPlayer

       AdPlayer_LinearAdListenerImplementor.java(54,54): Error:  error: cannot find symbol
               com.adtech.mobilesdk.publisher.vast.player.AdPlayer.LinearAdListener
                                                                  ^
       symbol:   class LinearAdListener
       location: class AdPlayer -->

  <remove-node path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.player']/interface[@name='AdPlayer.AdPodListener']" />
  <remove-node path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.player']/interface[@name='AdPlayer.AdPodPlayerListener']" />
  <remove-node path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.player']/interface[@name='AdPlayer.LandingPageListener']" />
  <remove-node path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.player']/interface[@name='AdPlayer.LinearAdListener']" />


  <!-- This type is not public. The same error would appear when
       attempting to use this interface in a Java Android app. So the
       binding for this type will not be needed and can be removed.

       MediaDownloadService_MediaDownloadListenerImplementor.java(65,65): Error:  error: MediaDownloadListener is not public in MediaDownloadService; cannot be accessed from outside package
               com.adtech.mobilesdk.publisher.vast.cache.MediaDownloadService.MediaDownloadListener -->
  <remove-node path="/api/package[@name='com.adtech.mobilesdk.publisher.vast.cache']/interface[@name='MediaDownloadService.MediaDownloadListener']" />