documentation: add some notes about Spring classes + nonnull by default return value

- fix #3458
- fix #3459

Author: jknack

jooby/src/main/java/io/jooby/annotation/package-info.java

@@ -0,0 +1,3 @@
+/** Supported annotations for creating MVC routes. */
+@edu.umd.cs.findbugs.annotations.ReturnValuesAreNonnullByDefault
+package io.jooby.annotation;

jooby/src/main/java/io/jooby/buffer/README

@@ -0,0 +1,10 @@
+Generic abstraction for working with byte buffer implementations.
+
+Copy from: https://github.com/spring-projects/spring-framework/tree/main/spring-core/src/main/java/org/springframework/core/io/buffer.
+
+- Copy all package inside io.jooby.byffer
+- remove all Assert/ObjectUtils import references
+- remove Netty5DataBuffer references
+- replace reactive stream classes references by JDK reactive streams
+- DataBufferUtils is a limited version of original - remove Deprecated methods
+- Remove all deprecated since 6.0 from DataBuffer and DataBufferFactory

jooby/src/main/java/io/jooby/buffer/package-info.java

@@ -1,3 +1,20 @@
+/*
+ * This file is part of Jooby.
+ *
+ * It is derived from Spring Framework, originally available at: https://github.com/spring-projects/spring-framework
+ *
+ * Spring Framework is licensed under the Apache License, Version 2.0.
+ *
+ * Modifications:
+ * - Code live inside of io.jooby.buffer package
+ * - Added DataBuffer.duplicate
+ * - Added DataBufferFactory.wrap(byte[] bytes, int offset, int length)
+ *
+ * Jooby is also licensed under the Apache License, Version 2.0.
+ *
+ * See the LICENSE file in the root of this repository for details.
+ */
+
 /**
  * Generic abstraction for working with byte buffer implementations.
  *
@@ -13,4 +30,5 @@
  *   <li>Remove all deprecated since 6.0 from DataBuffer and DataBufferFactory
  * </ul>
  */
+@edu.umd.cs.findbugs.annotations.ReturnValuesAreNonnullByDefault
 package io.jooby.buffer;

jooby/src/main/java/io/jooby/exception/package-info.java

@@ -0,0 +1,2 @@
+/** Built-in exceptions for common HTTP error codes. */
+package io.jooby.exception;

jooby/src/main/java/io/jooby/handler/package-info.java

@@ -0,0 +1,3 @@
+/** Built-in middleware. */
+@edu.umd.cs.findbugs.annotations.ReturnValuesAreNonnullByDefault
+package io.jooby.handler;

jooby/src/main/java/io/jooby/package-info.java

@@ -0,0 +1,23 @@
+/**
+ * Welcome to Jooby!
+ *
+ * <p>Hello World:
+ *
+ * <pre>{@code
+ * public class App extends Jooby {
+ *
+ *   {
+ *     get("/", ctx -> "Hello World!");
+ *   }
+ *
+ *   public static void main(String[] args) {
+ *     runApp(args, App::new);
+ *   }
+ * }
+ *
+ * }</pre>
+ *
+ * More documentation at <a href="https://jooby.io">jooby.io</a>
+ */
+@edu.umd.cs.findbugs.annotations.ReturnValuesAreNonnullByDefault
+package io.jooby;