fix(java): drop method refs flagged by null analysis

sdks/java/src/main/java/org/byteveda/taskito/resources/ResourceRuntime.java

@@ -385,7 +385,9 @@ private Object build(String name, ResourceDefinition definition, ResourceContext
     private void disposeWorker() {
         // Pools first: pooled instances may depend on worker resources, which the
         // teardown stack below disposes.
-        pools.values().forEach(ResourcePool::shutdown);
+        for (ResourcePool pool : pools.values()) {
+            pool.shutdown();
+        }
         pools.clear();
         synchronized (workerTeardown) {
             while (!workerTeardown.isEmpty()) {

sdks/java/src/main/java/org/byteveda/taskito/workflows/WorkflowAnalysis.java

@@ -55,7 +55,7 @@ public static List<String> topologicalOrder(Workflow workflow) {
             String node = ready.poll();
             order.add(node);
             for (String next : successors.getOrDefault(node, List.of())) {
-                indegree.merge(next, -1, Integer::sum);
+                indegree.merge(next, -1, (count, delta) -> count + delta);
                 if (indegree.get(next) == 0) {
                     ready.add(next);
                 }

sdks/java/src/test/java/org/byteveda/taskito/Greeter.java

@@ -13,6 +13,6 @@ String greet(String name) {
 
     @TaskHandler
     Integer total(List<Integer> numbers) {
-        return numbers.stream().mapToInt(Integer::intValue).sum();
+        return numbers.stream().mapToInt(number -> number.intValue()).sum();
     }
 }