Fix the isolated project violation

`dependency.group` would be accessed which, for project dependencies, would cause an isolated project violation. Now project dependencies are filtered out.

This partially fixes #4423

Closes #4570

RELNOTES=Fix project isolation violation when checking that Hilt libraries are applied along the Gradle plugin.
PiperOrigin-RevId: 714428280

Author: ansman

java/dagger/hilt/android/plugin/main/src/main/kotlin/dagger/hilt/android/plugin/HiltGradlePlugin.kt

@@ -51,6 +51,7 @@ import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.Task
 import org.gradle.api.artifacts.Configuration
+import org.gradle.api.artifacts.ExternalDependency
 import org.gradle.api.artifacts.component.ProjectComponentIdentifier
 import org.gradle.api.attributes.Attribute
 import org.gradle.api.provider.ProviderFactory
@@ -421,7 +422,9 @@ class HiltGradlePlugin @Inject constructor(private val providers: ProviderFactor
           it.name.startsWith("hiltAnnotationProcessor") || it.name.startsWith("hiltCompileOnly")
         }
         .flatMap { configuration ->
-          configuration.dependencies.map { dependency -> dependency.group to dependency.name }
+          configuration.dependencies.filterIsInstance<ExternalDependency>().map { dependency ->
+            dependency.group to dependency.name
+          }
         }
         .toSet()
     fun getMissingDepMsg(depCoordinate: String): String =