#84 - Made constructor in Resource package private.

This change is to essentially prevent people from subclassing Resource and call the default constructor which wrecks the assumption of content never being null. For custom resources extend ResourceSupport.

Added missing license header in ResourcesMixin.

src/main/java/org/springframework/hateoas/Resource.java

@@ -36,7 +36,7 @@ public class Resource<T> extends ResourceSupport {
 	/**
 	 * Creates an empty {@link Resource}.
 	 */
-	protected Resource() {
+	Resource() {
 		this.content = null;
 	}
 

src/main/java/org/springframework/hateoas/hal/ResourcesMixin.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2012-2013 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
+ *
+ *      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.
+ */
 package org.springframework.hateoas.hal;
 
 import java.util.Collection;