allow build on jdk14

Signed-off-by: Lukas Jungmann <lukas.jungmann@oracle.com>
diff --git a/.travis.yml b/.travis.yml
index 7f03c9b..54994b3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@
 
 jdk:
   - openjdk11
+  - openjdk14
 
 cache:
   directories:
diff --git a/api/src/main/javadoc/overview.html b/api/src/main/javadoc/overview.html
index fa7effa..9b7517b 100644
--- a/api/src/main/javadoc/overview.html
+++ b/api/src/main/javadoc/overview.html
@@ -1,7 +1,7 @@
 <html>
 <!--
 
-    Copyright (c) 2013, 2019 Oracle and/or its affiliates. All rights reserved.
+    Copyright (c) 2013, 2020 Oracle and/or its affiliates. All rights reserved.
 
     This program and the accompanying materials are made available under the
     terms of the Eclipse Public License v. 2.0, which is available at
@@ -40,7 +40,7 @@
 it is often not as efficient as the streaming model and requires more memory.
 The object model generates JSON output by navigating the entire tree at once.
 
-<h2>The Streaming API</h2>
+<h1>The Streaming API</h1>
 <p>The streaming API is similar to the StAX API for XML and consists of the
 interfaces {@link jakarta.json.stream.JsonParser} and
 {@link jakarta.json.stream.JsonGenerator}. {@code JsonParser}
@@ -65,7 +65,7 @@
 JSON data efficiently. Other JSON frameworks (such as JSON binding) can be
 implemented using this API.</p>
 
-<h2>The Object Model API</h2>
+<h1>The Object Model API</h1>
 <p>The object model API is similar to the DOM API for XML. It is a high-level
 API that provides immutable object models for JSON object and array structures.
 These JSON structures are represented as object models using the Java types
@@ -98,7 +98,7 @@
 how to write an empty {@code JsonObject} model using the interface
 {@code JsonWriter}.
 
-<h2>JSON Pointer, JSON Patch, and JSON Merge Patch</h2>
+<h1>JSON Pointer, JSON Patch, and JSON Merge Patch</h1>
 Jakarta JSON Processing supports the latest standard on
 <a href="http://tools.ietf.org/html/rfc6901">JSON Pointer</a>,
 <a Href="http://tools.ietf.org/html/rfc6902">JSON Patch</a>, and
diff --git a/impl/src/main/javadoc/overview.html b/impl/src/main/javadoc/overview.html
index d2e1a55..9b7517b 100644
--- a/impl/src/main/javadoc/overview.html
+++ b/impl/src/main/javadoc/overview.html
@@ -40,7 +40,7 @@
 it is often not as efficient as the streaming model and requires more memory.
 The object model generates JSON output by navigating the entire tree at once.
 
-<h2>The Streaming API</h2>
+<h1>The Streaming API</h1>
 <p>The streaming API is similar to the StAX API for XML and consists of the
 interfaces {@link jakarta.json.stream.JsonParser} and
 {@link jakarta.json.stream.JsonGenerator}. {@code JsonParser}
@@ -65,7 +65,7 @@
 JSON data efficiently. Other JSON frameworks (such as JSON binding) can be
 implemented using this API.</p>
 
-<h2>The Object Model API</h2>
+<h1>The Object Model API</h1>
 <p>The object model API is similar to the DOM API for XML. It is a high-level
 API that provides immutable object models for JSON object and array structures.
 These JSON structures are represented as object models using the Java types
@@ -98,7 +98,7 @@
 how to write an empty {@code JsonObject} model using the interface
 {@code JsonWriter}.
 
-<h2>JSON Pointer, JSON Patch, and JSON Merge Patch</h2>
+<h1>JSON Pointer, JSON Patch, and JSON Merge Patch</h1>
 Jakarta JSON Processing supports the latest standard on
 <a href="http://tools.ietf.org/html/rfc6901">JSON Pointer</a>,
 <a Href="http://tools.ietf.org/html/rfc6902">JSON Patch</a>, and