open-api: javadoc parser NPE

- fix #3840

Author: jknack

modules/jooby-openapi/src/main/java/io/jooby/internal/openapi/javadoc/JavaDocNode.java

@@ -156,11 +156,6 @@ public int getColumnNumber() {
           return 0;
         }
 
-        //        @Override
-        //        public DetailNode[] getChildren() {
-        //          return new DetailNode[0];
-        //        }
-
         @Override
         public DetailNode getParent() {
           return null;

modules/jooby-openapi/src/main/java/io/jooby/internal/openapi/javadoc/JavaDocStream.java

@@ -145,7 +145,7 @@ private static <T> Iterator<T> backwardIterator(ASTNode<T> node) {
 
       @Override
       public boolean hasNext() {
-        return it.getParent() != null;
+        return it.getNode() != null && it.getParent() != null;
       }
 
       @Override
@@ -163,14 +163,15 @@ private static <T> Iterator<T> forwardIterator(ASTNode<T> node, boolean full) {
 
       @Override
       public boolean hasNext() {
-        return it != null;
+        return it != null && it.getNode() != null;
       }
 
       @Override
       public T next() {
-        if (it.getNextSibling() != null) {
+        var sibling = it.getNextSibling();
+        if (sibling != null) {
           if (full || it != node) {
-            stack.push(it.getNextSibling());
+            stack.push(sibling);
           }
         }
         var current = it;
@@ -210,22 +211,26 @@ static ASTNode<DetailNode> javadoc(DetailNode node) {
     static <N> ASTNode<N> ast(
         N node, Function<N, N> parent, Function<N, N> child, Function<N, N> sibling) {
       return new ASTNode<>() {
-        @Override
-        public ASTNode<N> getParent() {
-          var parentNode = parent.apply(node);
-          if (parentNode == null) {
+
+        private ASTNode<N> apply(Function<N, N> fn) {
+          if (node == null) {
             return null;
           }
-          return ast(parentNode, parent, child, sibling);
+          var result = fn.apply(node);
+          if (result == null) {
+            return null;
+          }
+          return ast(result, parent, child, sibling);
+        }
+
+        @Override
+        public ASTNode<N> getParent() {
+          return apply(parent);
         }
 
         @Override
         public ASTNode<N> getFirstChild() {
-          var childNode = child.apply(node);
-          if (childNode == null) {
-            return null;
-          }
-          return ast(childNode, parent, child, sibling);
+          return apply(child);
         }
 
         @Override
@@ -235,11 +240,7 @@ public N getNode() {
 
         @Override
         public ASTNode<N> getNextSibling() {
-          var siblingNode = sibling.apply(node);
-          if (siblingNode == null) {
-            return null;
-          }
-          return ast(siblingNode, parent, child, sibling);
+          return apply(sibling);
         }
       };
     }

modules/jooby-openapi/src/test/java/issues/i3840/App3840.java

@@ -0,0 +1,16 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package issues.i3840;
+
+import static io.jooby.openapi.MvcExtensionGenerator.toMvcExtension;
+
+import io.jooby.Jooby;
+
+public class App3840 extends Jooby {
+  {
+    mvc(toMvcExtension(C3840.class));
+  }
+}

modules/jooby-openapi/src/test/java/issues/i3840/C3840.java

@@ -0,0 +1,21 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package issues.i3840;
+
+import java.util.concurrent.CompletableFuture;
+
+import io.jooby.annotation.GET;
+import io.jooby.annotation.Path;
+
+@Path("/3840")
+public class C3840 {
+
+  @GET
+  public CompletableFuture<String> hello() {
+    return CompletableFuture.supplyAsync(() -> "hello")
+        .whenComplete((e, o) -> o.printStackTrace()); // <- root cause line
+  }
+}

modules/jooby-openapi/src/test/java/issues/i3840/Issue3840.java

@@ -0,0 +1,18 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package issues.i3840;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import io.jooby.openapi.OpenAPIResult;
+import io.jooby.openapi.OpenAPITest;
+
+public class Issue3840 {
+  @OpenAPITest(value = App3840.class)
+  public void shouldNotThrowNPE(OpenAPIResult result) {
+    assertThat(result).isNotNull();
+  }
+}