APT NPE with empty controllers

- check if super-types is present, it won't be present on empty-controllers
- fix #3656

Stacktrace:
```
  Caused by: java.lang.NullPointerException: Cannot read field "context" because "parent" is null
  at io.jooby.internal.apt.MvcRouter.<init> (MvcRouter.java:39)
  at io.jooby.apt.JoobyProcessor.lambda$buildRouteRegistry$11 (JoobyProcessor.java:296)
  at java.util.HashMap.computeIfAbsent (HashMap.java:1220)
  at io.jooby.apt.JoobyProcessor.buildRouteRegistry (JoobyProcessor.java:296)
  at io.jooby.apt.JoobyProcessor.buildRouteRegistry (JoobyProcessor.java:219)
  at io.jooby.apt.JoobyProcessor.process (JoobyProcessor.java:109)
```

Author: jknack

modules/jooby-apt/src/main/java/io/jooby/apt/JoobyProcessor.java

@@ -292,8 +292,13 @@ private void buildRouteRegistry(Map<TypeElement, MvcRouter> registry, TypeElemen
                 });
       } else {
         if (!currentType.equals(superType)) {
-          // edge case when controller has no method and extends another class which has.
-          registry.computeIfAbsent(currentType, key -> new MvcRouter(key, registry.get(superType)));
+          // edge-case #1: when controller has no method and extends another class which has.
+          // edge-case #2: some odd usage a controller could be empty.
+          // See https://github.com/jooby-project/jooby/issues/3656
+          if (registry.containsKey(superType)) {
+            registry.computeIfAbsent(
+                currentType, key -> new MvcRouter(key, registry.get(superType)));
+          }
         }
       }
     }

modules/jooby-apt/src/test/java/io/jooby/apt/ProcessorRunner.java

@@ -12,10 +12,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 import java.util.function.Consumer;
 import java.util.stream.Stream;
 
@@ -147,7 +144,10 @@ public ProcessorRunner withSourceCode(SneakyThrows.Consumer<String> consumer) {
   }
 
   public ProcessorRunner withSourceCode(boolean kt, SneakyThrows.Consumer<String> consumer) {
-    consumer.accept(kt ? processor.kotlinSource : processor.getSource().toString());
+    consumer.accept(
+        kt
+            ? processor.kotlinSource
+            : Optional.ofNullable(processor.getSource()).map(Objects::toString).orElse(null));
     return this;
   }
 

modules/jooby-apt/src/test/java/tests/i3539/Issue3539.java

@@ -29,7 +29,7 @@ public void shouldGenerateAnnotationWithDefaultValue() throws Exception {
               assertNotNull(attributes);
               assertFalse(attributes.isEmpty());
               var secured = attributes.get(Secured3525.class.getSimpleName());
-              assertSame(secured, Boolean.TRUE);
+              assertSame(Boolean.TRUE, secured);
             });
   }
 }

modules/jooby-apt/src/test/java/tests/i3656/B3656.java

@@ -0,0 +1,11 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3656;
+
+import io.jooby.annotation.Path;
+
+@Path("/b3656")
+public class B3656 {}

modules/jooby-apt/src/test/java/tests/i3656/C3656.java

@@ -0,0 +1,11 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3656;
+
+import io.jooby.annotation.Path;
+
+@Path("/c3656")
+public class C3656 extends B3656 {}

modules/jooby-apt/src/test/java/tests/i3656/Issue3656.java

@@ -0,0 +1,18 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3656;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import io.jooby.apt.ProcessorRunner;
+
+public class Issue3656 {
+  @Test
+  public void shouldNotThrowErrorOnEmptyController() throws Exception {
+    new ProcessorRunner(new C3656()).withSourceCode(Assertions::assertNull);
+  }
+}