Rename UpdatableBootJars to ApexBootJars.

Note that ART apex boot jars and core-icu4j are exceptions here as they
are not part of ApexBootJars. ART apex boot jars are defined in their
own variable, while core-icu4j is treated as a regular non-updatable
boot jar.

Bug: 191127295
Test: atest CtsClasspathsTestCases
Change-Id: I3cea3d82ef521655a1a5ffa8cae2258ab9d08bfc
diff --git a/java/dexpreopt_bootjars.go b/java/dexpreopt_bootjars.go
index dff9543..3651cf6 100644
--- a/java/dexpreopt_bootjars.go
+++ b/java/dexpreopt_bootjars.go
@@ -167,10 +167,10 @@
 // regardless which APEX goes into the product. See also android.ApexInfo.ApexVariationName and
 // apex.apexBundleProperties.Apex_name.
 //
-// A related variable PRODUCT_UPDATABLE_BOOT_JARS contains bootclasspath libraries that are in
-// APEXes. They are not included in the boot image. The only exception here is core-icu4j.jar that
-// has been historically part of the boot image and is now in a non updatable apex; it is treated
-// as being part of PRODUCT_BOOT_JARS and is in the boot image.
+// A related variable PRODUCT_APEX_BOOT_JARS contains bootclasspath libraries that are in APEXes.
+// They are not included in the boot image. The only exception here are ART jars and core-icu4j.jar
+// that have been historically part of the boot image and are now in apexes; they are in boot images
+// and core-icu4j.jar is generally treated as being part of PRODUCT_BOOT_JARS.
 //
 // One exception to the above rules are "coverage" builds (a special build flavor which requires
 // setting environment variable EMMA_INSTRUMENT_FRAMEWORK=true). In coverage builds the Java code in
@@ -810,10 +810,10 @@
 
 // generateUpdatableBcpPackagesRule generates the rule to create the updatable-bcp-packages.txt file
 // and returns a path to the generated file.
-func generateUpdatableBcpPackagesRule(ctx android.ModuleContext, image *bootImageConfig, updatableModules []android.Module) android.WritablePath {
+func generateUpdatableBcpPackagesRule(ctx android.ModuleContext, image *bootImageConfig, apexModules []android.Module) android.WritablePath {
 	// Collect `permitted_packages` for updatable boot jars.
 	var updatablePackages []string
-	for _, module := range updatableModules {
+	for _, module := range apexModules {
 		if j, ok := module.(PermittedPackagesForUpdatableBootJars); ok {
 			pp := j.PermittedPackagesForUpdatableBootJars()
 			if len(pp) > 0 {