[Mono.Android] Generate default interface members for API-30+.

Author: jpobst

src/Mono.Android/Android.Telephony.Mbms/IGroupCallCallback.cs

@@ -5,7 +5,7 @@
 
 namespace Android.Telephony.Mbms
 {
-	public interface IGroupCallCallback : IJavaObject
+	public partial interface IGroupCallCallback : IJavaObject
 	{
 		// This is not generated because all the methods in this
 		// interface are default interface mthods, and the interface

src/Mono.Android/Mono.Android.csproj

@@ -11,6 +11,7 @@
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>..\..\product.snk</AssemblyOriginatorKeyFile>
     <NoWarn>0618;0809;0108;0114</NoWarn>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <Import Project="..\..\Configuration.props" />
   <PropertyGroup>

src/Mono.Android/Mono.Android.targets

@@ -98,9 +98,10 @@
       <_Api>$(IntermediateOutputPath)mcw\api.xml</_Api>
       <_Dirs>--enumdir=$(IntermediateOutputPath)mcw</_Dirs>
       <_FullIntermediateOutputPath>$([System.IO.Path]::GetFullPath('$(IntermediateOutputPath)'))</_FullIntermediateOutputPath>
+      <_LangFeatures Condition="$(AndroidApiLevel) &gt;= 30">--lang-features=default-interface-methods</_LangFeatures>
     </PropertyGroup>
     <Exec
-        Command="$(ManagedRuntime) $(ManagedRuntimeArgs) $(Generator) $(_GenFlags) $(_ApiLevel) $(_Out) $(_Codegen) $(_Fixup) $(_Enums1) $(_Enums2) $(_Versions) $(_Annotations) $(_Assembly) $(_TypeMap) $(_Dirs) $(_Api)"
+        Command="$(ManagedRuntime) $(ManagedRuntimeArgs) $(Generator) $(_GenFlags) $(_ApiLevel) $(_Out) $(_Codegen) $(_Fixup) $(_Enums1) $(_Enums2) $(_Versions) $(_Annotations) $(_Assembly) $(_TypeMap) $(_LangFeatures) $(_Dirs) $(_Api)"
     />
     <ItemGroup>
       <Compile Include="$(_FullIntermediateOutputPath)\mcw\**\*.cs" KeepDuplicates="False" />

src/Mono.Android/metadata

@@ -1551,4 +1551,10 @@
   <remove-node api-since="30" path="/api/package[@name='java.util']/interface[@jni-signature='Ljava/util/Map;']/method[@name='of' and count(parameter)=16]" />
   <remove-node api-since="30" path="/api/package[@name='java.util']/interface[@jni-signature='Ljava/util/Map;']/method[@name='of' and count(parameter)=18]" />
   <remove-node api-since="30" path="/api/package[@name='java.util']/interface[@jni-signature='Ljava/util/Map;']/method[@name='of' and count(parameter)=20]" />
+
+  <!-- Work around a generator bug where having multiple Listener methods with the same name cause multiple conflicting EventArgs classes to be created. -->
+  <!-- These are "default" method versions, so it's ok to remove them from an interface. -->
+  <remove-node api-since="30" path="/api/package[@name='android.animation']/interface[@name='Animator.AnimatorListener']/method[@name='onAnimationStart' and count(parameter)=2]" />
+  <remove-node api-since="30" path="/api/package[@name='android.animation']/interface[@name='Animator.AnimatorListener']/method[@name='onAnimationEnd' and count(parameter)=2]" />
+
 </metadata>