java_sdk_library: Correct stubs source generation classpath

The stubs source should be generated using the same classpath that is
used to compile the implementation library, i.e. sdk_version,
system_modules and libs/static_libs.

Previously, the sdk_version used to generate the stubs was different.
It provided access to a wider API surface than was necessary. This
change fixes that.

Test: m checkapi
Bug: 155164730
Change-Id: I7bc54dc4ad12a7d6c7503111d1322ee35c56d713
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 6fa3150..9e3ad5b 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -498,17 +498,15 @@
 		}
 	}{}
 
-	sdkDep := decodeSdkDep(mctx, sdkContext(&module.Library))
-	// Use the platform API if standard libraries were requested, otherwise use
-	// no default libraries.
-	sdkVersion := ""
-	if !sdkDep.hasStandardLibs() {
-		sdkVersion = "none"
-	}
+	// The stubs source processing uses the same compile time classpath when extracting the
+	// API from the implementation library as it does when compiling it. i.e. the same
+	// * sdk version
+	// * system_modules
+	// * libs (static_libs/libs)
 
 	props.Name = proptools.StringPtr(module.docsName(apiScope))
 	props.Srcs = append(props.Srcs, module.Library.Module.properties.Srcs...)
-	props.Sdk_version = proptools.StringPtr(sdkVersion)
+	props.Sdk_version = module.Library.Module.deviceProperties.Sdk_version
 	props.System_modules = module.Library.Module.deviceProperties.System_modules
 	props.Installable = proptools.BoolPtr(false)
 	// A droiddoc module has only one Libs property and doesn't distinguish between