jooby-apt: kotlin: should generates a code with !! null operator for nullable types

- fix #3507

Author: jknack

modules/jooby-apt/src/main/java/io/jooby/internal/apt/AnnotationSupport.java

@@ -17,6 +17,9 @@
 import javax.lang.model.element.VariableElement;
 
 public interface AnnotationSupport {
+  Predicate<String> NULLABLE = name -> name.toLowerCase().endsWith(".nullable");
+  Predicate<String> NON_NULL =
+      name -> name.toLowerCase().endsWith(".nonnull") || name.toLowerCase().endsWith(".notnull");
   Predicate<String> VALUE = "value"::equals;
   Predicate<String> NAME = "name"::equals;
 

modules/jooby-apt/src/main/java/io/jooby/internal/apt/MvcParameter.java

@@ -5,6 +5,9 @@
  */
 package io.jooby.internal.apt;
 
+import static io.jooby.internal.apt.AnnotationSupport.NON_NULL;
+import static io.jooby.internal.apt.AnnotationSupport.NULLABLE;
+
 import java.util.*;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -15,10 +18,6 @@
 import javax.lang.model.element.VariableElement;
 
 public class MvcParameter {
-  private static final Predicate<String> NULLABLE =
-      name -> name.toLowerCase().endsWith(".nullable");
-  private static final Predicate<String> NON_NULL =
-      name -> name.toLowerCase().endsWith(".nonnull") || name.toLowerCase().endsWith(".notnull");
   private final MvcRoute route;
   private final VariableElement parameter;
   private final Map<String, AnnotationMirror> annotations;

modules/jooby-apt/src/main/java/io/jooby/internal/apt/MvcRoute.java

@@ -209,7 +209,13 @@ public List<String> generateHandlerCall(boolean kt) {
     var returnTypeGenerics =
         getReturnType().getArgumentsString(kt, false, Set.of(TypeKind.TYPEVAR));
     var returnTypeString = type(kt, getReturnType().toString());
+    boolean nullable = false;
     if (kt) {
+      nullable =
+          method.getAnnotationMirrors().stream()
+              .map(AnnotationMirror::getAnnotationType)
+              .map(Objects::toString)
+              .anyMatch(NULLABLE);
       if (throwsException) {
         buffer.add(statement("@Throws(Exception::class)"));
       }
@@ -312,7 +318,7 @@ public List<String> generateHandlerCall(boolean kt) {
         setUncheckedCast(true);
         call = kt ? call + " as " + returnTypeString : "(" + returnTypeString + ") " + call;
       }
-      buffer.add(statement(indent(2), "return ", call, semicolon(kt)));
+      buffer.add(statement(indent(2), "return ", call, kt && nullable ? "!!" : "", semicolon(kt)));
     }
     buffer.add(statement("}", System.lineSeparator()));
     if (uncheckedCast) {

modules/jooby-apt/src/test/java/tests/i3507/C3507.java

@@ -0,0 +1,17 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3507;
+
+import edu.umd.cs.findbugs.annotations.Nullable;
+import io.jooby.annotation.GET;
+import io.jooby.annotation.QueryParam;
+
+public class C3507 {
+  @GET("/3507")
+  @Nullable public String get(@QueryParam String query) {
+    return null;
+  }
+}

modules/jooby-apt/src/test/java/tests/i3507/Issue3507.java

@@ -0,0 +1,27 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3507;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+import io.jooby.apt.ProcessorRunner;
+
+public class Issue3507 {
+
+  @Test
+  public void shouldGenerateNullSafeKtReturnType() throws IOException {
+    new ProcessorRunner(new C3507())
+        .withSource(
+            true,
+            source -> {
+              assertTrue(source.contains("return c.get(ctx.query(\"query\").value())!!"));
+            });
+  }
+}