chore: Allow Android bindings to be built using local maven artefacts

CONTRIBUTING.md

@@ -194,3 +194,20 @@ and let the next build download the pre-built SDK again:
 $ rm -rf modules/sentry-cocoa
 $ dotnet build ... # downloads pre-built Cocoa SDK into modules/sentry-cocoa
 ```
+
+## Local Sentry Android SDK checkout
+
+Similarly, by default, `Sentry.Bindings.Android` downloads a pre-built Sentry Android SDK from
+Maven. The version is specified in the `SentryAndroidSdkVersion` build property in `Sentry.Bindings.Android.csproj`.
+
+If you want to build an unreleased Sentry Android SDK version from source instead,
+you'll need to clone both the sentry-java and the sentry-native repositories and publish these locally:
+```sh
+$ cd $(LocalSentryJavaRepoDir) && ./gradlew publishToMavenLocal
+$ cd $(LocalSentryNativeRepoDir)/ndk && ./gradlew publishToMavenLocal
+```
+
+You'll also need to set `<UseLocalSentryMavenRepo>true</UseLocalSentryMavenRepo>` and `<SentryNativeNdkVersion>{whatever_version_you_checked_out}</SentryNativeNdkVersion>`
+in the `Sentry.Bindings.Android.csproj`file.
+
+To switch back again, simply revert those two build properties to their original values.

src/Sentry.Bindings.Android/README.md

@@ -6,7 +6,7 @@ Instead, reference one of the following:
 
 ## SDK Developers and Contributors
 
-For .NET SDK contributors, most of the classes in this package are generated automatically.
+For .NET SDK contributors, most of the classes in this package are generated automatically. These can be found in the `src/Sentry.Bindings.Android/obj/{Configuration}/{tfm}/generated/src/` folder after building the project.
 
 - Post generation transformations are controlled via various XML files stored in the `/Transforms` directory  (see [Java Bindings Metadata documentation](https://learn.microsoft.com/en-gb/previous-versions/xamarin/android/platform/binding-java-library/customizing-bindings/java-bindings-metadata) for details).
 

src/Sentry.Bindings.Android/Sentry.Bindings.Android.csproj

@@ -3,10 +3,37 @@
     <TargetFrameworks>$(LatestAndroidTfm);$(PreviousAndroidTfm)</TargetFrameworks>
     <SentryAndroidSdkVersion>8.29.0</SentryAndroidSdkVersion>
     <SentryAndroidSdkDirectory>$(BaseIntermediateOutputPath)sdks\$(TargetFramework)\Sentry\Android\$(SentryAndroidSdkVersion)\</SentryAndroidSdkDirectory>
-    <!-- This gets resolved by the DownloadSentryAndroidSdk target -->
+    <!-- This gets resolved by the DownloadSentryAndroidSdk unless using local maven references -->
     <SentryNativeNdkVersion></SentryNativeNdkVersion>
     <Description>.NET Bindings for the Sentry Android SDK</Description>
 
+    <!--
+      Optional dev override: enable to resolve local maven references
+      Example:
+        dotnet build -p:UseLocalSentryMavenRepo=true
+
+      To populate MavenLocal from your checkout:
+        cd $(LocalSentryJavaRepoDir) && ./gradlew publishToMavenLocal
+        cd $(LocalSentryNativeRepoDir)/ndk && ./gradlew publishToMavenLocal
+
+      Note:
+      1. Make sure the native-ndk-version you check out and build matches what the android sdk expects (or a fork of it)
+      2. You will need to manually set the `SentryNativeNdkVersion` property as this no longer gets resolved from
+         the POM files from the Java SDK when using local maven artifacts.
+    -->
+    <UseLocalSentryMavenRepo>false</UseLocalSentryMavenRepo>
+    <LocalSentryMavenRepoDir Condition="'$(LocalSentryMavenRepoDir)' == ''">$([System.Environment]::GetFolderPath(SpecialFolder.UserProfile))/.m2/repository/</LocalSentryMavenRepoDir>
+    <LocalSentryJarPath>$(LocalSentryMavenRepoDir)io/sentry/sentry/$(SentryAndroidSdkVersion)/sentry-$(SentryAndroidSdkVersion).jar</LocalSentryJarPath>
+    <LocalSentryAndroidCoreAarPath>$(LocalSentryMavenRepoDir)io/sentry/sentry-android-core/$(SentryAndroidSdkVersion)/sentry-android-core-$(SentryAndroidSdkVersion).aar</LocalSentryAndroidCoreAarPath>
+    <LocalSentryAndroidNdkAarPath>$(LocalSentryMavenRepoDir)io/sentry/sentry-android-ndk/$(SentryAndroidSdkVersion)/sentry-android-ndk-$(SentryAndroidSdkVersion).aar</LocalSentryAndroidNdkAarPath>
+    <LocalSentryAndroidReplayAarPath>$(LocalSentryMavenRepoDir)io/sentry/sentry-android-replay/$(SentryAndroidSdkVersion)/sentry-android-replay-$(SentryAndroidSdkVersion).aar</LocalSentryAndroidReplayAarPath>
+    <LocalSentryPomPath>$([System.String]::Copy($(LocalSentryJarPath)).Replace('.jar', '.pom'))</LocalSentryPomPath>
+    <LocalSentryAndroidCorePomPath>$([System.String]::Copy($(LocalSentryAndroidCoreAarPath)).Replace('.aar', '.pom'))</LocalSentryAndroidCorePomPath>
+    <LocalSentryAndroidNdkPomPath>$([System.String]::Copy($(LocalSentryAndroidNdkAarPath)).Replace('.aar', '.pom'))</LocalSentryAndroidNdkPomPath>
+    <LocalSentryAndroidReplayPomPath>$([System.String]::Copy($(LocalSentryAndroidReplayAarPath)).Replace('.aar', '.pom'))</LocalSentryAndroidReplayPomPath>
+    <LocalSentryNativeNdkAarPath>$(LocalSentryMavenRepoDir)io/sentry/sentry-native-ndk/$(SentryNativeNdkVersion)/sentry-native-ndk-$(SentryNativeNdkVersion).aar</LocalSentryNativeNdkAarPath>
+    <LocalSentryNativeNdkPomPath>$([System.String]::Copy($(LocalSentryNativeNdkAarPath)).Replace('.aar', '.pom'))</LocalSentryNativeNdkPomPath>
+
     <!-- Android binding warnings - these are largely unavoidable due to Java interface circular dependencies -->
     <!-- Only suppress warnings that are confirmed to be expected/unavoidable -->
     <!-- BG8801: Invalid parameter types - caused by circular interface dependencies in Sentry Java SDK -->
@@ -73,13 +100,27 @@
   </ItemGroup>
 
   <!-- Starting with .NET 9 we can detect Java dependencies using POM files and AndroidMavenLibrary references -->
-  <ItemGroup>
+  <ItemGroup Condition="'$(UseLocalSentryMavenRepo)' != 'true'">
     <AndroidMavenLibrary Include="io.sentry:sentry" Version="$(SentryAndroidSdkVersion)" />
     <AndroidMavenLibrary Include="io.sentry:sentry-android-core" Version="$(SentryAndroidSdkVersion)" />
     <AndroidMavenLibrary Include="io.sentry:sentry-android-ndk" Version="$(SentryAndroidSdkVersion)" />
     <AndroidMavenLibrary Include="io.sentry:sentry-android-replay" Version="$(SentryAndroidSdkVersion)" />
   </ItemGroup>
 
+  <!-- Resolve Java dependencies from local sentry-java build outputs instead, if appropriate -->
+  <ItemGroup Condition="'$(UseLocalSentryMavenRepo)' == 'true'">
+    <AndroidLibrary Include="$(LocalSentryJarPath)" Manifest="$(LocalSentryPomPath)"
+                    JavaArtifact="io.sentry:sentry:$(SentryAndroidSdkVersion)" />
+    <AndroidLibrary Include="$(LocalSentryAndroidCoreAarPath)" Manifest="$(LocalSentryAndroidCorePomPath)"
+                       JavaArtifact="io.sentry:sentry-android-core:$(SentryAndroidSdkVersion)" />
+    <AndroidLibrary Include="$(LocalSentryAndroidNdkAarPath)" Manifest="$(LocalSentryAndroidNdkPomPath)"
+                       JavaArtifact="io.sentry:sentry-android-ndk:$(SentryAndroidSdkVersion)" />
+    <AndroidLibrary Include="$(LocalSentryAndroidReplayAarPath)" Manifest="$(LocalSentryAndroidReplayPomPath)"
+                       JavaArtifact="io.sentry:sentry-android-replay:$(SentryAndroidSdkVersion)" />
+    <AndroidLibrary Include="$(LocalSentryNativeNdkAarPath)" Manifest="$(LocalSentryNativeNdkPomPath)"
+                       JavaArtifact="io.sentry:sentry-native-ndk:$(SentryNativeNdkVersion)" />
+  </ItemGroup>
+
   <ItemGroup>
     <AndroidLibrary Include="..\..\lib\sentry-android-supplemental\bin\sentry-android-supplemental.jar" />
     <AndroidNativeLibrary Include="..\..\lib\sentrysupplemental\bin\arm64-v8a\libsentrysupplemental.so" Abi="arm64-v8a" />
@@ -88,7 +129,7 @@
     <AndroidNativeLibrary Include="..\..\lib\sentrysupplemental\bin\x86_64\libsentrysupplemental.so" Abi="x86_64" />
   </ItemGroup>
 
-  <Target Name="DownloadSentryAndroidSdk" BeforeTargets="CollectPackageReferences">
+  <Target Name="DownloadSentryAndroidSdk" BeforeTargets="CollectPackageReferences" Condition="'$(UseLocalSentryMavenRepo)' != 'true'">
     <!-- The native-ndk exists outside of the android-ndk now. We're downloading the POM file to get the version of the native-ndk. -->
     <DownloadFile
       SourceUrl="https://repo1.maven.org/maven2/io/sentry/sentry-android-ndk/$(SentryAndroidSdkVersion)/sentry-android-ndk-$(SentryAndroidSdkVersion).pom"