Add better error handling to bootDexJar function

aosp/2876754 missed adding error handling to one of the places which
consumes the dex jar deapexed from prebuilt apexes. This CL ensures that
when we have multiple prebuilt apexes _without_ flagging, the hiddenapi
processing code emits a more descriptive error "Multiple deapxers..."
rather than a cryptic error "<module> does not provide a dex jar"

Test: m nothing --no-skip-soong-tests

Change-Id: I80849fa7cca17d724ac53c94bb353b169175ee28
diff --git a/java/hiddenapi.go b/java/hiddenapi.go
index e9ee3a2..5441a3b 100644
--- a/java/hiddenapi.go
+++ b/java/hiddenapi.go
@@ -44,7 +44,8 @@
 	//
 	// This must be the path to the unencoded dex jar as the encoded dex jar indirectly depends on
 	// this file so using the encoded dex jar here would result in a cycle in the ninja rules.
-	bootDexJarPath OptionalDexJarPath
+	bootDexJarPath    OptionalDexJarPath
+	bootDexJarPathErr error
 
 	// The paths to the classes jars that contain classes and class members annotated with
 	// the UnsupportedAppUsage annotation that need to be extracted as part of the hidden API
@@ -56,7 +57,10 @@
 	uncompressDexState *bool
 }
 
-func (h *hiddenAPI) bootDexJar() OptionalDexJarPath {
+func (h *hiddenAPI) bootDexJar(ctx android.ModuleErrorfContext) OptionalDexJarPath {
+	if h.bootDexJarPathErr != nil {
+		ctx.ModuleErrorf(h.bootDexJarPathErr.Error())
+	}
 	return h.bootDexJarPath
 }
 
@@ -77,7 +81,7 @@
 }
 
 type hiddenAPIIntf interface {
-	bootDexJar() OptionalDexJarPath
+	bootDexJar(ctx android.ModuleErrorfContext) OptionalDexJarPath
 	classesJars() android.Paths
 	uncompressDex() *bool
 }
@@ -126,6 +130,11 @@
 	h.active = isModuleInBootClassPath(ctx, module)
 }
 
+// Store any error encountered during the initialization of hiddenapi structure (e.g. unflagged co-existing prebuilt apexes)
+func (h *hiddenAPI) initHiddenAPIError(err error) {
+	h.bootDexJarPathErr = err
+}
+
 func isModuleInBootClassPath(ctx android.BaseModuleContext, module android.Module) bool {
 	// Get the configured platform and apex boot jars.
 	nonApexBootJars := ctx.Config().NonApexBootJars()
diff --git a/java/hiddenapi_modular.go b/java/hiddenapi_modular.go
index a512860..5176692 100644
--- a/java/hiddenapi_modular.go
+++ b/java/hiddenapi_modular.go
@@ -1342,7 +1342,7 @@
 // invalid, then create a fake path and either report an error immediately or defer reporting of the
 // error until the path is actually used.
 func retrieveBootDexJarFromHiddenAPIModule(ctx android.ModuleContext, module hiddenAPIModule) android.Path {
-	bootDexJar := module.bootDexJar()
+	bootDexJar := module.bootDexJar(ctx)
 	if !bootDexJar.Valid() {
 		fake := android.PathForModuleOut(ctx, fmt.Sprintf("fake/boot-dex/%s.jar", module.Name()))
 		handleMissingDexBootFile(ctx, module, fake, bootDexJar.InvalidReason())
diff --git a/java/java.go b/java/java.go
index 4eeded3..807aea9 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2258,6 +2258,7 @@
 				// An error was found, possibly due to multiple apexes in the tree that export this library
 				// Defer the error till a client tries to call DexJarBuildPath
 				j.dexJarFileErr = err
+				j.initHiddenAPIError(err)
 				return
 			}
 			dexJarFileApexRootRelative := ApexRootRelativePathToJavaLib(j.BaseModuleName())
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 058862b..ce94ff9 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -2769,6 +2769,7 @@
 				// An error was found, possibly due to multiple apexes in the tree that export this library
 				// Defer the error till a client tries to call DexJarBuildPath
 				module.dexJarFileErr = err
+				module.initHiddenAPIError(err)
 				return
 			}
 			dexJarFileApexRootRelative := ApexRootRelativePathToJavaLib(module.BaseModuleName())