V2 nhotfix (#2272)

* readme

* dewfault values

README.md

 | dismissOverlay             |  [Contribute](/docs/docs/CONTRIBUTING.md)         |	✅ |
 | customTransition            |   ✅        |	[Contribute](/docs/docs/CONTRIBUTING.md) |
 | Screen Visibility        | ✅     |✅|
-| async commands (await push)     |  [Contribute](/docs/docs/CONTRIBUTING.md)        |[Contribute](/docs/docs/CONTRIBUTING.md)   |
+| async commands (await push)     |  [Contribute](/docs/docs/CONTRIBUTING.md)        | WIP @cool04ek   |
 
 ### Navigation Options
 
 | splitViewScreen       |     :x:  |    [Contribute](/docs/docs/CONTRIBUTING.md)      | [Contribute](/docs/docs/CONTRIBUTING.md)|
 
 Element transitions, adding buttons and styles are not yet implemented. [Contribute](/docs/docs/CONTRIBUTING.md)  
-

lib/android/app/src/main/java/com/reactnativenavigation/parse/BottomTabsOptions.java

 	public int tabBadge = NO_INT_VALUE;
 	public NavigationOptions.BooleanOptions hidden = NavigationOptions.BooleanOptions.False;
 	public NavigationOptions.BooleanOptions animateHide = NavigationOptions.BooleanOptions.False;
-	public int currentTabIndex;
-	public String currentTabId;
+	public int currentTabIndex = NO_INT_VALUE;
+	public String currentTabId = NO_VALUE;
 
 	void mergeWith(final BottomTabsOptions other) {
 		if (!NO_VALUE.equals(other.currentTabId)) {
 			currentTabId = other.currentTabId;
 		}
-		if(NO_INT_VALUE != other.currentTabIndex) {
+		if (NO_INT_VALUE != other.currentTabIndex) {
 			currentTabId = other.currentTabId;
 		}
-		if(NO_INT_VALUE != other.tabBadge) {
+		if (NO_INT_VALUE != other.tabBadge) {
 			tabBadge = other.tabBadge;
 		}
 		if (other.hidden != NavigationOptions.BooleanOptions.NoValue) {

lib/android/app/src/main/java/com/reactnativenavigation/parse/TopBarOptions.java

 		return options;
 	}
 
-	public String title = "";
+	public String title = NO_VALUE;
 	@ColorInt
-	public int backgroundColor;
+	public int backgroundColor = NO_COLOR_VALUE;
 	@ColorInt
-	public int textColor;
-	public float textFontSize;
-	public String textFontFamily;
+	public int textColor = NO_COLOR_VALUE;
+	public float textFontSize = NO_FLOAT_VALUE;
+	public String textFontFamily = NO_VALUE;
 	public NavigationOptions.BooleanOptions hidden = NavigationOptions.BooleanOptions.False;
 	public NavigationOptions.BooleanOptions animateHide = NavigationOptions.BooleanOptions.False;