Merge pull request #706 from google/623

Fixed javadoc for JsonWriter as reported in

gson/src/main/java/com/google/gson/stream/JsonWriter.java

@@ -77,7 +77,7 @@ import static com.google.gson.stream.JsonScope.NONEMPTY_OBJECT;
  * This code encodes the above structure: <pre>   {@code
  *   public void writeJsonStream(OutputStream out, List<Message> messages) throws IOException {
  *     JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
- *     writer.setIndentSpaces(4);
+ *     writer.setIndent("    ");
  *     writeMessagesArray(writer, messages);
  *     writer.close();
  *   }