Add docs and copyright information

Add copyright information to all ConfigNode classes. Document
the ConfigNode interface.

config/src/main/java/com/typesafe/config/ConfigNode.java

@@ -1,5 +1,27 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config;
 
+/**
+ * An immutable node that makes up the ConfigDocument AST, and which can be
+ * used to reproduce part or all of the original text of an input.
+ *
+ * <p>
+ * Because this object is immutable, it is safe to use from multiple threads and
+ * there's no need for "defensive copies."
+ *
+ * <p>
+ * <em>Do not implement interface {@code ConfigNode}</em>; it should only be
+ * implemented by the config library. Arbitrary implementations will not work
+ * because the library internals assume a specific concrete implementation.
+ * Also, this interface is likely to grow new methods over time, so third-party
+ * implementations will break.
+ */
 public interface ConfigNode {
+    /**
+     * The original text of the input which was used to form this particular node.
+     * @return the original text used to form this node as a String
+     */
     public String render();
 }

config/src/main/java/com/typesafe/config/impl/AbstractConfigNode.java

@@ -1,3 +1,6 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import com.typesafe.config.ConfigNode;

config/src/main/java/com/typesafe/config/impl/AbstractConfigNodeValue.java

@@ -1,7 +1,9 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
-// This is gross. We currently have a class that doesn't do anything, but is needed
-// to distinguish certain types of nodes from other types. This is required if we want
+// This is required if we want
 // to be referencing the AbstractConfigNode class in implementation rather than the
 // ConfigNode interface, as we can't cast an AbstractConfigNode to an interface
 abstract class AbstractConfigNodeValue extends AbstractConfigNode {

config/src/main/java/com/typesafe/config/impl/ConfigNodeComplexValue.java

@@ -1,3 +1,6 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import com.typesafe.config.ConfigNode;

config/src/main/java/com/typesafe/config/impl/ConfigNodeKey.java

@@ -1,3 +1,6 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import java.util.Collection;

config/src/main/java/com/typesafe/config/impl/ConfigNodeKeyValue.java

@@ -1,3 +1,6 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import com.typesafe.config.ConfigException;
@@ -6,7 +9,7 @@ import com.typesafe.config.ConfigNode;
 import java.util.ArrayList;
 import java.util.Collection;
 
-public class ConfigNodeKeyValue extends AbstractConfigNode {
+final class ConfigNodeKeyValue extends AbstractConfigNode {
     final private ArrayList<AbstractConfigNode> children;
 
     public ConfigNodeKeyValue(Collection<AbstractConfigNode> children) {

config/src/main/java/com/typesafe/config/impl/ConfigNodeSimpleValue.java

@@ -1,13 +1,13 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import java.util.Collection;
 import java.util.Collections;
 
-/**
- * This class represents a leaf ConfigNode. This type of ConfigNode has no children.
- */
 class ConfigNodeSimpleValue extends AbstractConfigNodeValue {
-    Token token;
+    final Token token;
     ConfigNodeSimpleValue(Token value) {
         token = value;
     }

config/src/main/java/com/typesafe/config/impl/ConfigNodeSingleToken.java

@@ -1,10 +1,13 @@
+/**
+ *   Copyright (C) 2015 Typesafe Inc. <http://typesafe.com>
+ */
 package com.typesafe.config.impl;
 
 import java.util.Collection;
 import java.util.Collections;
 
 final class ConfigNodeSingleToken extends AbstractConfigNode{
-    Token token;
+    final Token token;
     ConfigNodeSingleToken(Token t) {
         token = t;
     }