Convert Note class

- Menu > "Code" > "Convert Java File to Kotlin File"
- Kotlin generates and hides getters/setters.
  + Getter/setter can be customized manually.
- This case is lucky. Normally there are some errors about
  + Nullable check
  + Lambda conversions
  + other non-standard Java features

app/src/main/java/com/udacity/notepad/data/Note.kt

@@ -0,0 +1,11 @@
+package com.udacity.notepad.data
+
+import java.util.Date
+
+class Note {
+    var id = -1
+    var text: String? = null
+    var isPinned = false
+    var createdAt = Date()
+    var updatedAt: Date? = null
+}