Use filegroup

Use filegroup to specify sources files with base directory via 'path'
property. This allows the build system to filter Java source files by
their packages.

Bug: 140764681
Test: m
Change-Id: I52760b3cbe3c99f5c48473f667322d6102cb7f53
diff --git a/openjdk_java_files.bp b/openjdk_java_files.bp
index d1ddf04..28d7af8 100644
--- a/openjdk_java_files.bp
+++ b/openjdk_java_files.bp
@@ -1345,6 +1345,7 @@
         "ojluni/src/main/java/javax/sql/StatementEventListener.java",
         "ojluni/src/main/java/sun/reflect/CallerSensitive.java",
     ],
+    path: "ojluni/src/main/java",
 }
 
 // Stubs needed to satisfy javac's dependencies when compiling lambda code. These are