Register java_plugin in PrepareForTestWithJavaBuildComponents

Bug: 182885307
Test: m nothing
Change-Id: I550d39ba46c548b6b099d8dc6a9c458ca931b2fa
diff --git a/java/testing.go b/java/testing.go
index b0290dc..82a2103 100644
--- a/java/testing.go
+++ b/java/testing.go
@@ -44,6 +44,7 @@
 	android.PrepareForTestWithAndroidBuildComponents,
 	// Make java build components available to the test.
 	android.FixtureRegisterWithContext(RegisterRequiredBuildComponentsForTest),
+	android.FixtureRegisterWithContext(registerJavaPluginBuildComponents),
 )
 
 // Test fixture preparer that will define default java modules, e.g. standard prebuilt modules.