Update copyright years to 2021.

Closes #616

multi-store/src/main/java/example/springdata/multistore/ApplicationConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2021 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.

multi-store/src/main/java/example/springdata/multistore/customer/Address.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2021 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.

multi-store/src/main/java/example/springdata/multistore/customer/Customer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2021 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.

multi-store/src/main/java/example/springdata/multistore/customer/CustomerRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2021 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.

multi-store/src/main/java/example/springdata/multistore/shop/LineItem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2021 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.

multi-store/src/main/java/example/springdata/multistore/shop/Order.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2021 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.

multi-store/src/main/java/example/springdata/multistore/shop/OrderRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2021 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.