Ensure namespace is specified for all the 3rd party libraries

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/ReactPlugin.kt

@@ -15,6 +15,7 @@ import com.facebook.react.tasks.GenerateCodegenSchemaTask
 import com.facebook.react.utils.AgpConfiguratorUtils.configureBuildConfigFieldsForApp
 import com.facebook.react.utils.AgpConfiguratorUtils.configureBuildConfigFieldsForLibraries
 import com.facebook.react.utils.AgpConfiguratorUtils.configureDevPorts
+import com.facebook.react.utils.AgpConfiguratorUtils.configureNamespaceForLibraries
 import com.facebook.react.utils.BackwardCompatUtils.configureBackwardCompatibilityReactMap
 import com.facebook.react.utils.DependencyUtils.configureDependencies
 import com.facebook.react.utils.DependencyUtils.configureRepositories
@@ -82,6 +83,7 @@ class ReactPlugin : Plugin<Project> {
 
     // Library Only Configuration
     configureBuildConfigFieldsForLibraries(project)
+    configureNamespaceForLibraries(project)
     project.pluginManager.withPlugin("com.android.library") {
       configureCodegen(project, extension, rootExtension, isLibrary = true)
     }

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/AgpConfiguratorUtils.kt

@@ -14,6 +14,11 @@ import com.facebook.react.utils.ProjectUtils.isNewArchEnabled
 import org.gradle.api.Action
 import org.gradle.api.Project
 import org.gradle.api.plugins.AppliedPlugin
+import java.io.File
+import com.android.build.gradle.LibraryExtension
+import javax.xml.parsers.DocumentBuilder
+import javax.xml.parsers.DocumentBuilderFactory
+import org.w3c.dom.Element
 
 @Suppress("UnstableApiUsage")
 internal object AgpConfiguratorUtils {
@@ -63,6 +68,40 @@ internal object AgpConfiguratorUtils {
     project.pluginManager.withPlugin("com.android.application", action)
     project.pluginManager.withPlugin("com.android.library", action)
   }
-}
 
+  fun configureNamespaceForLibraries(appProject: Project) {
+    appProject.rootProject.allprojects { subproject ->
+      subproject.pluginManager.withPlugin("com.android.library") {
+        subproject.extensions.getByType(AndroidComponentsExtension::class.java).finalizeDsl { ext ->
+          if(ext.namespace == null){
+            val android = subproject.extensions.getByType(LibraryExtension::class.java)
+            val manifestFile = android.sourceSets.getByName("main").manifest.srcFile
+
+            manifestFile.takeIf { it.exists() }?.let { file ->
+              getPackageNameFromManifest(file)?.let { packageName ->
+                 ext.namespace = packageName
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
 const val DEFAULT_DEV_SERVER_PORT = "8081"
+
+fun getPackageNameFromManifest(manifest: File): String? {
+  val factory: DocumentBuilderFactory = DocumentBuilderFactory.newInstance()
+  val builder: DocumentBuilder = factory.newDocumentBuilder()
+
+  try {
+    val xmlDocument = builder.parse(manifest)
+
+    val manifestElement = xmlDocument.getElementsByTagName("manifest").item(0) as? Element
+    val packageName = manifestElement?.getAttribute("package")
+
+    return if (packageName.isNullOrEmpty()) null else packageName
+  } catch (e: Exception) {
+    return null
+  }
+}

packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/AgpConfiguratorUtilsTest.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.utils
+
+import java.io.File
+import org.junit.Assert.*
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+
+class AgpConfiguratorUtilsTest {
+
+  @get:Rule val tempFolder = TemporaryFolder()
+
+  @Test
+  fun getPackageNameFromManifest_withEmptyFile_returnsNull() {
+    val mainFolder = tempFolder.newFolder("awesome-module/src/main/")
+    val manifest = File(mainFolder, "AndroidManifest.xml").apply {
+      writeText("")
+    }
+
+    val actual = getPackageNameFromManifest(manifest)
+    assertNull(actual)
+  }
+
+  @Test
+  fun getPackageNameFromManifest_withMissingPackage_returnsNull() {
+    val mainFolder = tempFolder.newFolder("awesome-module/src/main/")
+    val manifest = File(mainFolder, "AndroidManifest.xml").apply {
+      writeText(
+          // language=xml
+          """
+          <manifest xmlns:android="http://schemas.android.com/apk/res/android">
+          </manifest>
+          """
+              .trimIndent())
+    }
+
+    val actual = getPackageNameFromManifest(manifest)
+    assertNull(actual)
+  }
+
+  @Test
+  fun getPackageNameFromManifest_withPackage_returnsPackage() {
+    val mainFolder = tempFolder.newFolder("awesome-module/src/main/")
+    val manifest = File(mainFolder, "AndroidManifest.xml").apply {
+      writeText(
+          // language=xml
+          """
+          <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.facebook.react" >
+          </manifest>
+          """
+              .trimIndent())
+    }
+
+    val actual = getPackageNameFromManifest(manifest)
+    assertNotNull(actual)
+    assertEquals("com.facebook.react", actual)
+  }
+}