Parallelize singleton execution

Bug: 281536768
Test: manual, presubmits
Change-Id: I57fdc76ba6b277e88e196b506af87127a530fd37
diff --git a/java/java.go b/java/java.go
index bb8fe62..33846be 100644
--- a/java/java.go
+++ b/java/java.go
@@ -73,8 +73,8 @@
 		ctx.BottomUp("jacoco_deps", jacocoDepsMutator).Parallel()
 	})
 
-	ctx.RegisterSingletonType("logtags", LogtagsSingleton)
-	ctx.RegisterSingletonType("kythe_java_extract", kytheExtractJavaFactory)
+	ctx.RegisterParallelSingletonType("logtags", LogtagsSingleton)
+	ctx.RegisterParallelSingletonType("kythe_java_extract", kytheExtractJavaFactory)
 }
 
 func RegisterJavaSdkMemberTypes() {