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[Java.Interop, generator] Fix GetPeerMembers for interfaces (#486)
Context: dotnet/android#3533 Consider the following Java interface which contains a default interface method: // Java package com.xamarin.android; public interface DefaultMethodsInterface { default int foo () { return 0; } } This is bound as: // C# Binding public partial interface IDefaultMethodsInterface : IJavaPeerable { static readonly JniPeerMembers _members = new JniPeerMembers ( "java/DefaultMethodsInterface", typeof (IDefaultMethodsInterface)); [Register ("foo", "()V", "…")] virtual unsafe int Foo () { return _members.InstanceMethods.InvokeVirtualInt32Method ("foo.()V", this, null); } } If we "implement" the interface from C# *without* implementing `IDefaultMethodsInterface.Foo()`: // C# class ManagedOverrideDefault : Java.Lang.Object, IDefaultMethodsInterface { } Then invoke the default interface method: var over = new ManagedOverrideDefault (); (over as IDefaultMethodsInterface).Foo (); The attempt to invoke the default implementation of `IDefaultMethodsInterface.Foo()` causes a crash: Java.Lang.NoSuchMethodError : no non-static method "Ljava/lang/Object;.foo()I" The cause of the crash is as follows: `IDefaultMethodsInterface.Foo()` calls `JniPeerMembers.JniInstanceMethods.InvokeVirtualInt32Method()` tries to determine if the method is overridden, and if the method is *not* overridden -- as is the case here -- then we hit the non-virtual invocation path: // src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods_Invoke.cs var j = Members.GetPeerMembers (self); var n = j.InstanceMethods.GetMethodInfo (encodedMember); return JniEnvironment.InstanceMethods.CallNonvirtualIntMethod (self.PeerReference, j.JniPeerType.PeerReference, n, parameters); `JniInstanceMethods.Members` will be the `IDefaultMethodsInterface._members` field, and `Members.GetPeerMembers()` would return `self.JniPeerMembers`. Because this is a C# class which inherits `Java.Lang.Object`, `Java.Lang.Object._members` is returned. We then attempt to resolve `foo()` from `java.lang.Object`, which *does not exist*, which is why the `NoSuchMethodError` is thrown. The fix is to "intercept" the `Members.GetPeerMembers()` invocation so that `j` refers to `IDefaultMethodsInterface._members`, *not* `Java.Lang.Object._members`. This would allow `n` to refer to `DefaultMethodsInterface.foo()`, which *does* exist, and *can* be invoked via `JniEnvironment.InstanceMethods.CallNonvirtualIntMethod()`. Add the following `JniPeerMembers` constructor overload: partial class JniPeerMembers { public JniPeerMembers (string jniPeerTypeName, Type managedPeerType, bool isInterface); } Update `JniPeerMembers.GetPeerMembers()` so that if `isInterface` is true, we return `this` (the *interface*s `JniPeerMembers` instance). Update `generator` so that `_members` construction within interfaces sets the `isInterface` parameter to true, resulting in: partial interface IDefaultMethodsInterface { static readonly JniPeerMembers _members = new JniPeerMembers ( "java/DefaultMethodsInterface", typeof (IDefaultMethodsInterface), isInterface: true); } This allows `(over as IDefaultMethodsInterface).Foo()` to work without an exception being thrown.
1 parent 29f9707 commit 3fee05c

9 files changed

Lines changed: 25 additions & 15 deletions

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‎gendarme-ignore.txt‎

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Original file line numberDiff line numberDiff line change
@@ -351,6 +351,7 @@ T: Java.Interop.JniInt32ArrayElements
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T: Java.Interop.JniInt64ArrayElements
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T: Java.Interop.JniLocationException
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T: Java.Interop.JniMethodInfo
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T: Java.Interop.JniPeerMembers
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T: Java.Interop.JniSByteArrayElements
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T: Java.Interop.JniSingleArrayElements
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T: Java.Interop.JniType

‎src/Java.Interop/Java.Interop/JniPeerMembers.cs‎

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@@ -7,8 +7,15 @@ namespace Java.Interop {
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public partial class JniPeerMembers {
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private bool isInterface;
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public JniPeerMembers (string jniPeerTypeName, Type managedPeerType, bool isInterface)
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: this (jniPeerTypeName, managedPeerType, checkManagedPeerType: true, isInterface: isInterface)
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{
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}
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public JniPeerMembers (string jniPeerTypeName, Type managedPeerType)
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: this (jniPeerTypeName, managedPeerType, checkManagedPeerType: true)
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: this (jniPeerTypeName, managedPeerType, checkManagedPeerType: true, isInterface: false)
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{
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if (managedPeerType == null)
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throw new ArgumentNullException ("managedPeerType");
@@ -27,7 +34,7 @@ public JniPeerMembers (string jniPeerTypeName, Type managedPeerType)
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ManagedPeerType = managedPeerType;
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}
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JniPeerMembers (string jniPeerTypeName, Type managedPeerType, bool checkManagedPeerType)
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JniPeerMembers (string jniPeerTypeName, Type managedPeerType, bool checkManagedPeerType, bool isInterface = false)
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{
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if (jniPeerTypeName == null)
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throw new ArgumentNullException (nameof (jniPeerTypeName));
@@ -51,6 +58,8 @@ public JniPeerMembers (string jniPeerTypeName, Type managedPeerType)
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JniPeerTypeName = jniPeerTypeName;
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ManagedPeerType = managedPeerType;
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this.isInterface = isInterface;
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instanceMethods = new JniInstanceMethods (this);
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instanceFields = new JniInstanceFields (this);
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staticMethods = new JniStaticMethods (this);
@@ -140,7 +149,7 @@ protected virtual bool UsesVirtualDispatch (IJavaPeerable value, Type declaringT
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protected virtual JniPeerMembers GetPeerMembers (IJavaPeerable value)
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{
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return value.JniPeerMembers;
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return isInterface ? this : value.JniPeerMembers;
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}
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internal static void AssertSelf (IJavaPeerable self)

‎tools/generator/Java.Interop.Tools.Generator.CodeGeneration/JavaInteropCodeGenerator.cs‎

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@@ -29,7 +29,7 @@ static string GetInvokeType (string type)
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internal override void WriteClassHandle (ClassGen type, string indent, bool requireNew)
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{
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WritePeerMembers (indent + '\t', true, requireNew, type.RawJniName, type.Name);
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WritePeerMembers (indent + '\t', true, requireNew, type.RawJniName, type.Name, false);
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writer.WriteLine ("{0}\tinternal static {1}IntPtr class_ref {{", indent, requireNew ? "new " : string.Empty);
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writer.WriteLine ("{0}\t\tget {{", indent);
@@ -55,12 +55,12 @@ internal override void WriteClassHandle (ClassGen type, string indent, bool requ
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internal override void WriteClassHandle (InterfaceGen type, string indent, string declaringType)
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{
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WritePeerMembers (indent, false, true, type.RawJniName, declaringType);
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WritePeerMembers (indent, false, true, type.RawJniName, declaringType, type.Name == declaringType);
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}
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internal override void WriteClassInvokerHandle (ClassGen type, string indent, string declaringType)
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{
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WritePeerMembers (indent, true, true, type.RawJniName, declaringType);
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WritePeerMembers (indent, true, true, type.RawJniName, declaringType, false);
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writer.WriteLine ();
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writer.WriteLine ("{0}public override global::Java.Interop.JniPeerMembers JniPeerMembers {{", indent);
@@ -75,7 +75,7 @@ internal override void WriteClassInvokerHandle (ClassGen type, string indent, st
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internal override void WriteInterfaceInvokerHandle (InterfaceGen type, string indent, string declaringType)
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{
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WritePeerMembers (indent, true, true, type.RawJniName, declaringType);
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WritePeerMembers (indent, true, true, type.RawJniName, declaringType, false);
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writer.WriteLine ();
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writer.WriteLine ("{0}static IntPtr java_class_ref {{", indent);
@@ -262,10 +262,10 @@ internal override void WriteFieldSetBody (Field field, string indent, GenBase ty
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writer.WriteLine ("{0}}}", indent);
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}
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void WritePeerMembers (string indent, bool isInternal, bool isNew, string rawJniType, string declaringType)
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void WritePeerMembers (string indent, bool isInternal, bool isNew, string rawJniType, string declaringType, bool isInterface)
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{
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var signature = $"{(isInternal ? "internal " : "")}static {(isNew ? "new " : "")}readonly JniPeerMembers _members = ";
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var type = $"new {GetPeerMembersType ()} (\"{rawJniType}\", typeof ({declaringType}));";
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var type = $"new {GetPeerMembersType ()} (\"{rawJniType}\", typeof ({declaringType}){(isInterface ? ", isInterface: true" : string.Empty)});";
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writer.WriteLine ($"{indent}{signature}{type}");
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}

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/JavaInterop1/WriteInterfaceDefaultMethod.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_DoSomething;
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#pragma warning disable 0169

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/JavaInterop1/WriteInterfaceDefaultProperty.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_get_Value;
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#pragma warning disable 0169

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/JavaInterop1/WriteInterfaceDefaultPropertyGetterOnly.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new JniPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_get_Value;
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#pragma warning disable 0169

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1/WriteInterfaceDefaultMethod.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_DoSomething;
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#pragma warning disable 0169

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1/WriteInterfaceDefaultProperty.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_get_Value;
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#pragma warning disable 0169

‎tools/generator/Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1/WriteInterfaceDefaultPropertyGetterOnly.txt‎

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@@ -1,7 +1,7 @@
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// Metadata.xml XPath interface reference: path="/api/package[@name='java.code']/interface[@name='IMyInterface']"
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[Register ("java/code/IMyInterface", "", "java.code.IMyInterfaceInvoker")]
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public partial interface IMyInterface : IJavaObject, IJavaPeerable {
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface));
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static new readonly JniPeerMembers _members = new XAPeerMembers ("java/code/IMyInterface", typeof (IMyInterface), isInterface: true);
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static Delegate cb_get_Value;
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#pragma warning disable 0169

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