diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..0fa18e5
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,22 @@
+<!--/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  ~ Licensed to the Apache Software Foundation (ASF) under one
+  ~ or more contributor license agreements.  See the NOTICE file
+  ~ distributed with this work for additional information
+  ~ regarding copyright ownership.  The ASF licenses this file
+  ~ to you under the Apache License, Version 2.0 (the
+  ~ "License"); you may not use this file except in compliance
+  ~ with the License.  You may obtain a copy of the License at
+  ~
+  ~   http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing,
+  ~ software distributed under the License is distributed on an
+  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  ~ KIND, either express or implied.  See the License for the
+  ~ specific language governing permissions and limitations
+  ~ under the License.
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/-->
+Apache Software Foundation Code of Conduct
+====
+
+Being an Apache project, Apache Sling adheres to the Apache Software Foundation's [Code of Conduct](https://www.apache.org/foundation/policies/conduct.html).
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..ac82a1a
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,24 @@
+<!--/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  ~ Licensed to the Apache Software Foundation (ASF) under one
+  ~ or more contributor license agreements.  See the NOTICE file
+  ~ distributed with this work for additional information
+  ~ regarding copyright ownership.  The ASF licenses this file
+  ~ to you under the Apache License, Version 2.0 (the
+  ~ "License"); you may not use this file except in compliance
+  ~ with the License.  You may obtain a copy of the License at
+  ~
+  ~   http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing,
+  ~ software distributed under the License is distributed on an
+  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  ~ KIND, either express or implied.  See the License for the
+  ~ specific language governing permissions and limitations
+  ~ under the License.
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/-->
+Contributing
+====
+
+Thanks for choosing to contribute!
+
+You will find all the necessary details about how you can do this at https://sling.apache.org/contributing.html.
diff --git a/pom.xml b/pom.xml
index 0aa7d14..3ed89b7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -28,7 +28,7 @@
     </parent>
 
     <artifactId>org.apache.sling.api</artifactId>
-    <version>2.18.5-SNAPSHOT</version>
+    <version>2.20.1-SNAPSHOT</version>
     <packaging>bundle</packaging>
 
     <name>Apache Sling API</name>
diff --git a/src/main/java/org/apache/sling/api/request/RequestPathInfo.java b/src/main/java/org/apache/sling/api/request/RequestPathInfo.java
index 90dce48..ce07ae3 100644
--- a/src/main/java/org/apache/sling/api/request/RequestPathInfo.java
+++ b/src/main/java/org/apache/sling/api/request/RequestPathInfo.java
@@ -52,11 +52,12 @@
  * request URI, the extension is empty.
  * <li>{@link #getSuffix() suffix path} - If the request URI contains a slash
  * character after the content path and optional selectors and extension, the
- * path starting with the slash upto the end of the request URI is the suffix
+ * path starting with the slash up to the end of the request URI is the suffix
  * path.
  * </ol>
  * <p>
- * Examples: <table summary="">
+ * Examples: <table>
+ * <caption>URI decomposition</caption>
  * <tr>
  * <th>URI</th>
  * <th>Content Path</th>
diff --git a/src/main/java/org/apache/sling/api/resource/AbstractResourceVisitor.java b/src/main/java/org/apache/sling/api/resource/AbstractResourceVisitor.java
index 20f8fc3..e152a5f 100644
--- a/src/main/java/org/apache/sling/api/resource/AbstractResourceVisitor.java
+++ b/src/main/java/org/apache/sling/api/resource/AbstractResourceVisitor.java
@@ -23,11 +23,13 @@
 import org.jetbrains.annotations.NotNull;
 
 /**
- * The <code>AbstractResourceVisitor</code> helps in traversing a
- * resource tree by decoupling the actual traversal code
- * from application code. Concrete subclasses should implement
- * the {@link AbstractResourceVisitor#visit(Resource)} method.
+ * This visitor will traverse the given resource and all its children in a breadth-first approach
+ * and call the {@link AbstractResourceVisitor#visit(Resource)} method for each visited resource.
+ * It decouples the actual traversal code from application code. 
+ * 
+ * Concrete subclasses must implement the {@link AbstractResourceVisitor#visit(Resource)} method.
  *
+ * @see <a href="https://en.wikipedia.org/wiki/Breadth-first_search">Breadth-First-Search</a>
  * @since 2.2 (Sling API Bundle 2.2.0)
  */
 public abstract class AbstractResourceVisitor {
diff --git a/src/main/java/org/apache/sling/api/resource/ResourceResolver.java b/src/main/java/org/apache/sling/api/resource/ResourceResolver.java
index c3b476d..8a2b27d 100644
--- a/src/main/java/org/apache/sling/api/resource/ResourceResolver.java
+++ b/src/main/java/org/apache/sling/api/resource/ResourceResolver.java
@@ -57,7 +57,8 @@
  * <code>resolve</code> methods and the <code>getResource</code> methods. The
  * difference lies in the algorithm applied to find the requested resource and
  * in the behavior in case a resource cannot be found:
- * <table summary="">
+ * <table>
+ *     <caption>Accessing Resources</caption>
  * <tr>
  * <th>Method Kind</th>
  * <th>Access Algorithm</th>
@@ -198,6 +199,7 @@
      * @throws IllegalStateException if this resource resolver has already been
      *             {@link #close() closed}.
      * @since 2.0.4 (Sling API Bundle 2.0.4)
+     * @see <a href="https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html">Mappings for Resource Resolution</a>
      */
     @NotNull Resource resolve(@NotNull HttpServletRequest request, @NotNull String absPath);
 
@@ -226,6 +228,7 @@
      *             thrown if an error occurs trying to resolve the resource.
      * @throws IllegalStateException if this resource resolver has already been
      *             {@link #close() closed}.
+     * @see <a href="https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html">Mappings for Resource Resolution</a>
      */
     @NotNull Resource resolve(@NotNull String absPath);
 
@@ -253,12 +256,13 @@
      *             {@link #close() closed}.
      * @deprecated as of 2.0.4, use {@link #resolve(HttpServletRequest, String)}
      *             instead.
+     * @see <a href="https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html">Mappings for Resource Resolution</a>
      */
     @Deprecated
     @NotNull Resource resolve(@NotNull HttpServletRequest request);
 
     /**
-     * Returns a path mapped from the (resource) path applying the reverse
+     * Returns a (request) path mapped from the (resource) path applying the reverse
      * mapping used by the {@link #resolve(String)} such that when the path is
      * given to the {@link #resolve(String)} method the same resource is
      * returned.
@@ -272,13 +276,20 @@
      * <p>
      * This method is intended as the reverse operation of the
      * {@link #resolve(String)} method.
+     * <p>
+     * This method also does percent-encoding before returning the (request) path
+     * (with charset UTF-8). Due to this calling this method multiple times in a nested 
+     * fashion might lead to an invalid (request) path which can subsequently not
+     * be resolved via {@link #resolve(String)}. 
      *
      * @param resourcePath The path for which to return a mapped path.
      * @return The mapped path.
      * @throws IllegalStateException if this resource resolver has already been
      *             {@link #close() closed}.
      * 
-     * @see {@link ResourceMapper#getMapping(String, HttpServletRequest)}
+     * @see ResourceMapper#getMapping(String, HttpServletRequest)
+     * @see <a href="https://tools.ietf.org/html/rfc3986#section-2.1">Percent-Encoding</a>
+     * @see <a href="https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html">Mappings for Resource Resolution</a>
      */
     @NotNull String map(@NotNull String resourcePath);
 
@@ -300,6 +311,11 @@
      * {@link #resolve(HttpServletRequest, String)} method. As such the URL
      * returned is expected to be an absolute URL including scheme, host, any
      * servlet context path and the actual path used to resolve the resource.
+     * <p>
+     * This method also does percent-encoding before returning the URL
+     * (with charset UTF-8). Due to this calling this method multiple times in a nested 
+     * fashion might lead to an invalid URL which can subsequently not
+     * be resolved via {@link #resolve(String)}. 
      *
      * @param request The http servlet request object which may be used to apply
      *            more mapping functionality.
@@ -309,7 +325,9 @@
      *             {@link #close() closed}.
      * @since 2.0.4 (Sling API Bundle 2.0.4)
      * 
-     * @see {@link ResourceMapper#getMapping(String, HttpServletRequest)}
+     * @see ResourceMapper#getMapping(String, HttpServletRequest)
+     * @see <a href="https://tools.ietf.org/html/rfc3986#section-2.1">Percent-Encoding</a>
+     * @see <a href="https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html">Mappings for Resource Resolution</a>
      */
     @Nullable String map(@NotNull HttpServletRequest request, @NotNull String resourcePath);
 
diff --git a/src/main/java/org/apache/sling/api/resource/mapping/ResourceMapper.java b/src/main/java/org/apache/sling/api/resource/mapping/ResourceMapper.java
index 53086d5..a302469 100644
--- a/src/main/java/org/apache/sling/api/resource/mapping/ResourceMapper.java
+++ b/src/main/java/org/apache/sling/api/resource/mapping/ResourceMapper.java
@@ -96,7 +96,7 @@
     @NotNull String getMapping(@NotNull String resourcePath, @NotNull HttpServletRequest request);
     
     /**
-     * Retuns all possible mappings for a given <tt>resourcePath</tt> as paths.
+     * Returns all possible mappings for a given {@code resourcePath} as paths.
      * 
      * <p>
      * This method differs from the {@link #getMapping(String)} variant
@@ -114,7 +114,7 @@
     Collection<String> getAllMappings(@NotNull String resourcePath);
 
     /**
-     * Retuns all possible mappings for a given <tt>resourcePath</tt> as URLs.
+     * Returns all possible mappings for a given {@code resourcePath} as URLs.
      * 
      * <p>
      * This method differs from the {@link #getMapping(String, HttpServletRequest)} variant
diff --git a/src/main/java/org/apache/sling/api/resource/path/PathBuilder.java b/src/main/java/org/apache/sling/api/resource/path/PathBuilder.java
index f7f3334..72c9950 100644
--- a/src/main/java/org/apache/sling/api/resource/path/PathBuilder.java
+++ b/src/main/java/org/apache/sling/api/resource/path/PathBuilder.java
@@ -19,7 +19,7 @@
 package org.apache.sling.api.resource.path;
 
 /**
- * The <tt>PathBuilder</tt> offers a convenient way of creating a valid path from multiple fragments
+ * The {@code PathBuilder} offers a convenient way of creating a valid path from multiple fragments
  *
  * @since 1.0.0 (Sling API Bundle 2.11.0)
  */
@@ -28,7 +28,7 @@
     private final StringBuilder sb = new StringBuilder();
 
     /**
-     * Creates a new <tt>PathBuilder</tt> instance
+     * Creates a new {@code PathBuilder} instance
      *
      * @param path the initial path
      */
@@ -76,4 +76,4 @@
     public String toString() {
         return sb.toString();
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/java/org/apache/sling/api/servlets/ServletResolverConstants.java b/src/main/java/org/apache/sling/api/servlets/ServletResolverConstants.java
index 9ce3d08..b1caca6 100644
--- a/src/main/java/org/apache/sling/api/servlets/ServletResolverConstants.java
+++ b/src/main/java/org/apache/sling/api/servlets/ServletResolverConstants.java
@@ -64,6 +64,17 @@
     public static final String SLING_SERVLET_RESOURCE_TYPES = "sling.servlet.resourceTypes";
 
     /**
+     * The name of the service registration property of a servlet registered as
+     * a service containing the resource super type supported by the servlet (value
+     * is "sling.servlet.resourceSuperType").
+     * <p>
+     * The type of this property is a String denoting the resource super type. This
+     * property is ignored if the {@link #SLING_SERVLET_RESOURCE_TYPES} property is
+     * not set. Otherwise this property is optional and ignored if not set.
+     */
+    public static final String SLING_SERVLET_RESOURCE_SUPER_TYPE = "sling.servlet.resourceSuperType";
+
+    /**
      * <p>
      * The name of the service registration property of a servlet registered as
      * a service providing the prefix/index to be used to register this servlet.
diff --git a/src/main/java/org/apache/sling/api/servlets/package-info.java b/src/main/java/org/apache/sling/api/servlets/package-info.java
index b018388..bb2595a 100644
--- a/src/main/java/org/apache/sling/api/servlets/package-info.java
+++ b/src/main/java/org/apache/sling/api/servlets/package-info.java
@@ -17,7 +17,7 @@
  * under the License.
  */
 
-@Version("2.2.1")
+@Version("2.3.0")
 package org.apache.sling.api.servlets;
 
 import org.osgi.annotation.versioning.Version;