Support '20NN-present' format in headers

Closes gh-448

Author: philwebb

spring-javaformat/spring-javaformat-checkstyle/src/main/java/io/spring/javaformat/checkstyle/check/SpringHeaderCheck.java

@@ -61,7 +61,7 @@ public class SpringHeaderCheck extends AbstractFileSetCheck {
 	/**
 	 * The default header copyright pattern.
 	 */
-	public static final String DEFAULT_HEADER_COPYRIGHT_PATTERN = "20\\d\\d(-20\\d\\d)?";
+	public static final String DEFAULT_HEADER_COPYRIGHT_PATTERN = "20\\d\\d(-20\\d\\d|-present)?";
 
 	private static final String DEFAULT_CHARSET = System.getProperty("file.encoding", StandardCharsets.UTF_8.name());
 

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/check/HeaderWithDateToPresent.txt

@@ -0,0 +1 @@
++0 errors

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/source/HeaderWithDateToPresent.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2019-present the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.
+ */
+
+/**
+ * The header uses NNNN-present.
+ *
+ * @author Phillip Webb
+ */
+public class HeaderWithDateToPresent {
+
+}

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/source/HeaderWithSingleDate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2019 the original author or authors.
+ * Copyright 2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.