Avoid hiddenapi ignoring prebuilt with missing dex implementation jar

Previously, when a prebuilt was preferred but did not provide a
suitable boot dex jar both the source and the prebuilt were silently
ignored which meant that the "hiddenapi list" command was not given a
complete set of boot dex jars. That could either lead to incorrect
hiddenapi flags being set or the "hiddenapi list" command failing if it
could not find a class. Debugging the cause of either of those cases
can be very time consuming so this change fails early and makes the
cause very explicit.

Bug: 181267622
Test: m nothing
Change-Id: I6763ddb9ba90ed2e501d0cf7984f6655237e905d
diff --git a/java/hiddenapi_singleton_test.go b/java/hiddenapi_singleton_test.go
index c0f0e38..fb63820 100644
--- a/java/hiddenapi_singleton_test.go
+++ b/java/hiddenapi_singleton_test.go
@@ -126,6 +126,29 @@
 `, indexParams)
 }
 
+func TestHiddenAPISingletonWithSourceAndPrebuiltPreferredButNoDex(t *testing.T) {
+	config := testConfigWithBootJars(`
+		java_library {
+			name: "foo",
+			srcs: ["a.java"],
+			compile_dex: true,
+		}
+
+		java_import {
+			name: "foo",
+			jars: ["a.jar"],
+			prefer: true,
+		}
+	`, []string{"platform:foo"}, nil)
+
+	ctx := testContextWithHiddenAPI(config)
+
+	runWithErrors(t, ctx, config,
+		"hiddenapi has determined that the source module \"foo\" should be ignored as it has been"+
+			" replaced by the prebuilt module \"prebuilt_foo\" but unfortunately it does not provide a"+
+			" suitable boot dex jar")
+}
+
 func TestHiddenAPISingletonWithPrebuilt(t *testing.T) {
 	ctx, _ := testHiddenAPIBootJars(t, `
 		java_import {