Java APIs used by Mainline modules.

Add scripts to generate java APIs used by Mainline modules. This is
aosp/1879177 with fixed build error that caused by dexdeps analyzing
resource only APKs which doesn't contains any .dex files. Now skip the
error generates in that case in gen_java_usedby_apex.sh

Forrest run:https://android-build.googleplex.com/builds/abtd/run/L38900000951898586

Test: TARGET_BUILD_APPS=com.android.adbd m dist apps_only
Change-Id: Id539cbe1b7306ace69c047f95ffc02265a467511
diff --git a/apex/apex.go b/apex/apex.go
index 33188cb..20660d3 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -424,8 +424,9 @@
 	isCompressed bool
 
 	// Path of API coverage generate file
-	apisUsedByModuleFile   android.ModuleOutPath
-	apisBackedByModuleFile android.ModuleOutPath
+	nativeApisUsedByModuleFile   android.ModuleOutPath
+	nativeApisBackedByModuleFile android.ModuleOutPath
+	javaApisUsedByModuleFile     android.ModuleOutPath
 
 	// Collect the module directory for IDE info in java/jdeps.go.
 	modulePaths []string