Create checkstyle file

Signed-off-by: Otavio Santana <otaviopolianasantana@gmail.com>

checkstyle.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (c) 2019 Otavio Santana and others
+  ~
+  ~ This program and the accompanying materials are made available under the
+  ~ terms of the Eclipse Public License v. 2.0 which is available at
+  ~ http://www.eclipse.org/legal/epl-2.0.
+  ~
+  ~ This Source Code may also be made available under the following Secondary
+  ~ Licenses when the conditions for such availability set forth in the Eclipse
+  ~ Public License v. 2.0 are satisfied: GNU General Public License, version 2
+  ~ with the GNU Classpath Exception which is available at
+  ~ https://www.gnu.org/software/classpath/license.html.
+  ~
+  ~ SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+  -->
+<!DOCTYPE module PUBLIC
+        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">