Implement dismissAllModals

android/app/src/main/java/com/reactnativenavigation/controllers/ModalController.java

 
 import java.lang.ref.WeakReference;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.Map;
 
 /**
         mModals.put(navigatorId, new WeakReference<>(modal));
     }
 
+    public boolean isModalDisplayed() {
+        return mModals.size() != 0;
+    }
+
     public boolean isModalDisplayed(String navigatorId) {
         return mModals.size() != 0 && mModals.containsKey(navigatorId);
     }
             mModals.remove(navigatorId);
         }
     }
+
+    public void dismissAllModals() {
+        Iterator<String> iterator = mModals.keySet().iterator();
+        while (iterator.hasNext()) {
+            WeakReference<RnnModal> ref = mModals.get(iterator.next());
+            RnnModal modal = RefUtils.get(ref);
+            if (modal != null) {
+                modal.dismiss();
+            }
+        }
+    }
 }

android/app/src/main/java/com/reactnativenavigation/modules/RctActivityModule.java

             });
         }
     }
+
+    @ReactMethod
+    public void dismissAllModals(final ReadableMap params) {
+        final BaseReactActivity context = ContextProvider.getActivityContext();
+        if (context != null && !context.isFinishing()) {
+        context.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                ModalController modalController = ModalController.getInstance();
+                if (modalController.isModalDisplayed()) {
+                    modalController.dismissAllModals();
+                }
+            }
+        });
+        }
+    }
 }

android/app/src/main/res/anim/slide_up.xml

     <translate
         android:fromYDelta="100%"
         android:toYDelta="0"
-        android:duration="350"/>
+        android:duration="250"/>
 </set>

src/platformSpecific.android.js

   RctActivity.showModal(params);
 }
 
+function dismissAllModals(params) {
+  RctActivity.dismissAllModals(params.animationType);
+}
+
 function addNavigatorParams(screen, navigator = null, idx = '') {
   screen.navigatorID = navigator ? navigator.navigatorID : utils.getRandomId() + '_nav' + idx;
   screen.screenInstanceID = utils.getRandomId();
   startSingleScreenApp,
   navigatorPush,
   navigatorPop,
-  showModal
+  showModal,
+  dismissAllModals
 }