Address some more PR feedback

Make the javadoc string for the ConfigDocument interface more
explicit about what it does with the value string when setting
a value. Add support for parsing a reader into a ConfigDocument.

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

@@ -24,7 +24,9 @@ public interface ConfigDocument {
      * at the final occurrence of the path. If the path does not exist, it will be added.
      *
      * @param path the path at which to set the desired value
-     * @param newValue the value to set at the desired path
+     * @param newValue the value to set at the desired path, represented as a string. This
+     *                 string will be parsed into a ConfigNode, and the text will be inserted
+     *                 as-is into the document, with leading and trailing whitespace removed.
      * @return a copy of the ConfigDocument with the desired value at the desired path
      */
     ConfigDocument setValue(String path, String newValue);

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

@@ -4,6 +4,7 @@ import com.typesafe.config.impl.ConfigImpl;
 import com.typesafe.config.impl.Parseable;
 
 import java.io.File;
+import java.io.Reader;
 
 /**
  * Factory for automatically creating a ConfigDocument from a given input. Currently
@@ -11,6 +12,34 @@ import java.io.File;
  */
 public final class ConfigDocumentFactory {
 
+    /**
+     * Parses a Reader into a ConfigDocument instance.
+     *
+     * @param reader
+     *       the reader to parse
+     * @param options
+     *       parse options to control how the reader is interpreted
+     * @return the parsed configuration
+     * @throws ConfigException on IO or parse errors
+     */
+    public static ConfigDocument parseReader(Reader reader, ConfigParseOptions options) {
+        return Parseable.newReader(reader, options).parseConfigDocument();
+    }
+
+    /**
+     * Parses a reader into a Config instance as with
+     * {@link #parseReader(Reader,ConfigParseOptions)} but always uses the
+     * default parse options.
+     *
+     * @param reader
+     *       the reader to parse
+     * @return the parsed configuration
+     * @throws ConfigException on IO or parse errors
+     */
+    public static ConfigDocument parseReader(Reader reader) {
+        return parseReader(reader, ConfigParseOptions.defaults());
+    }
+
     /**
      * Parses a file into a ConfigDocument instance.
      *

config/src/test/scala/com/typesafe/config/impl/ConfigDocumentTest.scala

@@ -198,4 +198,11 @@ class ConfigDocumentTest extends TestUtils {
         val fileText = sb.toString()
         assertEquals(fileText, configDocument.render())
     }
+
+    @Test
+    def configDocumentReaderParse {
+        val configDocument = ConfigDocumentFactory.parseReader(new FileReader(resourceFile("/test03.conf")))
+        val configDocumentFile = ConfigDocumentFactory.parseFile(resourceFile("/test03.conf"))
+        assertEquals(configDocumentFile.render(), configDocument.render())
+    }
 }