Migrate from old-style legacy .java provider to the new JavaInfo

Change-Id: I360158ac6b5c053826fca288b025400f873f37da
diff --git a/tools/pkg_war.bzl b/tools/pkg_war.bzl
index 888e162..2952a03 100644
--- a/tools/pkg_war.bzl
+++ b/tools/pkg_war.bzl
@@ -56,8 +56,8 @@
 
     transitive_libs = []
     for l in ctx.attr.libs:
-        if hasattr(l, "java"):
-            transitive_libs.append(l.java.transitive_runtime_deps)
+        if JavaInfo in l:
+            transitive_libs.append(l[JavaInfo].transitive_runtime_deps)
         elif hasattr(l, "files"):
             transitive_libs.append(l.files)
 
@@ -74,8 +74,8 @@
     transitive_context_libs = []
     if ctx.attr.context:
         for jar in ctx.attr.context:
-            if hasattr(jar, "java"):
-                transitive_context_libs.append(jar.java.transitive_runtime_deps)
+            if JavaInfo in jar:
+                transitive_context_libs.append(jar[JavaInfo].transitive_runtime_deps)
             elif hasattr(jar, "files"):
                 transitive_context_libs.append(jar.files)
     transitive_context_deps = depset(transitive = transitive_context_libs)