Dont merge null colors

When updating a tab icon, if null was used as color - it would get applied.

lib/android/app/src/main/java/com/reactnativenavigation/presentation/BottomTabPresenter.java

 import com.reactnativenavigation.parse.BottomTabOptions;
 import com.reactnativenavigation.parse.DotIndicatorOptions;
 import com.reactnativenavigation.parse.Options;
+import com.reactnativenavigation.parse.params.Param;
 import com.reactnativenavigation.utils.ImageLoader;
 import com.reactnativenavigation.utils.ImageLoadingListenerAdapter;
 import com.reactnativenavigation.utils.LateInit;
             if (index >= 0) {
                 BottomTabOptions tab = options.bottomTabOptions;
                 if (tab.fontFamily != null) bottomTabs.setTitleTypeface(index, tab.fontFamily);
-                if (tab.selectedIconColor.hasValue()) bottomTabs.setIconActiveColor(index, tab.selectedIconColor.get());
-                if (tab.iconColor.hasValue()) bottomTabs.setIconInactiveColor(index, tab.iconColor.get());
+                if (canMerge(tab.selectedIconColor)) bottomTabs.setIconActiveColor(index, tab.selectedIconColor.get());
+                if (canMerge(tab.iconColor)) bottomTabs.setIconInactiveColor(index, tab.iconColor.get());
                 if (tab.selectedTextColor.hasValue()) bottomTabs.setTitleActiveColor(index, tab.selectedTextColor.get());
                 if (tab.textColor.hasValue()) bottomTabs.setTitleInactiveColor(index, tab.textColor.get());
                 if (tab.text.hasValue()) bottomTabs.setText(index, tab.text.get());
     private boolean shouldApplyDot(BottomTabOptions tab) {
         return tab.dotIndicator.visible.hasValue() && !tab.badge.hasValue();
     }
+
+    private boolean canMerge(Param p) {
+        return p.hasValue() && p.canApplyValue();
+    }
 }

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/BottomTabPresenterTest.java

 import com.reactnativenavigation.mocks.SimpleViewController;
 import com.reactnativenavigation.parse.Options;
 import com.reactnativenavigation.parse.params.Colour;
+import com.reactnativenavigation.parse.params.DontApplyColour;
 import com.reactnativenavigation.parse.params.Text;
 import com.reactnativenavigation.presentation.BottomTabPresenter;
 import com.reactnativenavigation.views.BottomTabs;
         verifyNoMoreInteractions(bottomTabs);
     }
 
+    @Test
+    public void mergeChildOptions_nullColorsAreNotMerged() {
+        Options options = new Options();
+        options.bottomTabOptions.iconColor = new DontApplyColour();
+        options.bottomTabOptions.selectedIconColor = new DontApplyColour();
+        uut.mergeChildOptions(options, (Component) child3.getView());
+        verify(bottomTabs, times(0)).setIconActiveColor(anyInt(), anyInt());
+        verify(bottomTabs, times(0)).setIconInactiveColor(anyInt(), anyInt());
+    }
+
     private Options createTab1Options() {
         Options options = new Options();
         options.bottomTabOptions.badge = new Text("tab1badge");