diff --git a/src/com/android/launcher3/PendingAddItemInfo.java b/src/com/android/launcher3/PendingAddItemInfo.java
index be994ee..b7a22fc 100644
--- a/src/com/android/launcher3/PendingAddItemInfo.java
+++ b/src/com/android/launcher3/PendingAddItemInfo.java
@@ -18,6 +18,7 @@
 
 import android.content.ComponentName;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.launcher3.model.data.ItemInfo;
@@ -43,6 +44,7 @@
     /**
      * Returns shallow copy of the object.
      */
+    @NonNull
     @Override
     public ItemInfo makeShallowCopy() {
         PendingAddItemInfo itemInfo = new PendingAddItemInfo();
diff --git a/src/com/android/launcher3/model/ItemInstallQueue.java b/src/com/android/launcher3/model/ItemInstallQueue.java
index 229bb2d..69f9b53 100644
--- a/src/com/android/launcher3/model/ItemInstallQueue.java
+++ b/src/com/android/launcher3/model/ItemInstallQueue.java
@@ -288,6 +288,7 @@
         }
 
         @Override
+        @Nullable
         public Intent getIntent() {
             return intent;
         }
diff --git a/src/com/android/launcher3/model/data/AppInfo.java b/src/com/android/launcher3/model/data/AppInfo.java
index 24e7dd3..34972e7 100644
--- a/src/com/android/launcher3/model/data/AppInfo.java
+++ b/src/com/android/launcher3/model/data/AppInfo.java
@@ -29,6 +29,7 @@
 import android.os.UserManager;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 
 import com.android.launcher3.LauncherSettings;
@@ -65,6 +66,7 @@
     }
 
     @Override
+    @Nullable
     public Intent getIntent() {
         return intent;
     }
diff --git a/src/com/android/launcher3/model/data/FolderInfo.java b/src/com/android/launcher3/model/data/FolderInfo.java
index 8386adb..524b769 100644
--- a/src/com/android/launcher3/model/data/FolderInfo.java
+++ b/src/com/android/launcher3/model/data/FolderInfo.java
@@ -26,6 +26,7 @@
 
 import android.os.Process;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.launcher3.LauncherSettings;
@@ -154,7 +155,7 @@
     }
 
     @Override
-    public void onAddToDatabase(ContentWriter writer) {
+    public void onAddToDatabase(@NonNull ContentWriter writer) {
         super.onAddToDatabase(writer);
         writer.put(LauncherSettings.Favorites.TITLE, title)
                 .put(LauncherSettings.Favorites.OPTIONS, options);
@@ -206,8 +207,9 @@
         return String.format("%s; labelState=%s", super.dumpProperties(), getLabelState());
     }
 
+    @NonNull
     @Override
-    public LauncherAtom.ItemInfo buildProto(FolderInfo fInfo) {
+    public LauncherAtom.ItemInfo buildProto(@Nullable FolderInfo fInfo) {
         FolderIcon.Builder folderIcon = FolderIcon.newBuilder()
                 .setCardinality(contents.size());
         if (LabelState.SUGGESTED.equals(getLabelState())) {
@@ -261,6 +263,7 @@
                                 : LabelState.SUGGESTED;
     }
 
+    @NonNull
     @Override
     public ItemInfo makeShallowCopy() {
         FolderInfo folderInfo = new FolderInfo();
@@ -272,6 +275,7 @@
     /**
      * Returns {@link LauncherAtom.FolderIcon} wrapped as {@link LauncherAtom.ItemInfo} for logging.
      */
+    @NonNull
     @Override
     public LauncherAtom.ItemInfo buildProto() {
         return buildProto(null);
diff --git a/src/com/android/launcher3/model/data/ItemInfo.java b/src/com/android/launcher3/model/data/ItemInfo.java
index 1e8e3ca..466f63f 100644
--- a/src/com/android/launcher3/model/data/ItemInfo.java
+++ b/src/com/android/launcher3/model/data/ItemInfo.java
@@ -42,6 +42,7 @@
 import android.os.Process;
 import android.os.UserHandle;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.launcher3.LauncherSettings;
@@ -141,30 +142,34 @@
     /**
      * Title of the item
      */
+    @Nullable
     public CharSequence title;
 
     /**
      * Content description of the item.
      */
+    @Nullable
     public CharSequence contentDescription;
 
     /**
      * When the instance is created using {@link #copyFrom}, this field is used to keep track of
      * original {@link ComponentName}.
      */
+    @Nullable
     private ComponentName mComponentName;
 
+    @NonNull
     public UserHandle user;
 
     public ItemInfo() {
         user = Process.myUserHandle();
     }
 
-    protected ItemInfo(ItemInfo info) {
+    protected ItemInfo(@NonNull final ItemInfo info) {
         copyFrom(info);
     }
 
-    public void copyFrom(ItemInfo info) {
+    public void copyFrom(@NonNull final ItemInfo info) {
         id = info.id;
         title = info.title;
         cellX = info.cellX;
@@ -182,6 +187,7 @@
         mComponentName = info.getTargetComponent();
     }
 
+    @Nullable
     public Intent getIntent() {
         return null;
     }
@@ -209,7 +215,7 @@
                         : null;
     }
 
-    public void writeToValues(ContentWriter writer) {
+    public void writeToValues(@NonNull final ContentWriter writer) {
         writer.put(LauncherSettings.Favorites.ITEM_TYPE, itemType)
                 .put(LauncherSettings.Favorites.CONTAINER, container)
                 .put(LauncherSettings.Favorites.SCREEN, screenId)
@@ -220,7 +226,7 @@
                 .put(LauncherSettings.Favorites.RANK, rank);
     }
 
-    public void readFromValues(ContentValues values) {
+    public void readFromValues(@NonNull final ContentValues values) {
         itemType = values.getAsInteger(LauncherSettings.Favorites.ITEM_TYPE);
         container = values.getAsInteger(LauncherSettings.Favorites.CONTAINER);
         screenId = values.getAsInteger(LauncherSettings.Favorites.SCREEN);
@@ -234,7 +240,7 @@
     /**
      * Write the fields of this item to the DB
      */
-    public void onAddToDatabase(ContentWriter writer) {
+    public void onAddToDatabase(@NonNull final ContentWriter writer) {
         if (Workspace.EXTRA_EMPTY_SCREEN_IDS.contains(screenId)) {
             // We should never persist an item on the extra empty screen.
             throw new RuntimeException("Screen id should not be extra empty screen: " + screenId);
@@ -245,10 +251,12 @@
     }
 
     @Override
+    @NonNull
     public final String toString() {
         return getClass().getSimpleName() + "(" + dumpProperties() + ")";
     }
 
+    @NonNull
     protected String dumpProperties() {
         return "id=" + id
                 + " type=" + LauncherSettings.Favorites.itemTypeToString(itemType)
@@ -288,14 +296,17 @@
     /**
      * Creates {@link LauncherAtom.ItemInfo} with important fields and parent container info.
      */
+    @NonNull
     public LauncherAtom.ItemInfo buildProto() {
         return buildProto(null);
     }
 
     /**
      * Creates {@link LauncherAtom.ItemInfo} with important fields and parent container info.
+     * @param fInfo
      */
-    public LauncherAtom.ItemInfo buildProto(FolderInfo fInfo) {
+    @NonNull
+    public LauncherAtom.ItemInfo buildProto(@Nullable final FolderInfo fInfo) {
         LauncherAtom.ItemInfo.Builder itemBuilder = getDefaultItemInfoBuilder();
         Optional<ComponentName> nullableComponent = Optional.ofNullable(getTargetComponent());
         switch (itemType) {
@@ -373,6 +384,7 @@
         return itemBuilder.build();
     }
 
+    @NonNull
     protected LauncherAtom.ItemInfo.Builder getDefaultItemInfoBuilder() {
         LauncherAtom.ItemInfo.Builder itemBuilder = LauncherAtom.ItemInfo.newBuilder();
         itemBuilder.setIsWork(!Process.myUserHandle().equals(user));
@@ -383,6 +395,7 @@
     /**
      * Returns {@link ContainerInfo} used when logging this item.
      */
+    @NonNull
     public ContainerInfo getContainerInfo() {
         switch (container) {
             case CONTAINER_HOTSEAT:
@@ -447,6 +460,7 @@
      * Returns non-AOSP container wrapped by {@link ExtendedContainers} object. Should be overridden
      * by build variants.
      */
+    @NonNull
     protected ExtendedContainers getExtendedContainer() {
         return ExtendedContainers.getDefaultInstance();
     }
@@ -454,6 +468,7 @@
     /**
      * Returns shallow copy of the object.
      */
+    @NonNull
     public ItemInfo makeShallowCopy() {
         ItemInfo itemInfo = new ItemInfo();
         itemInfo.copyFrom(this);
@@ -463,7 +478,8 @@
     /**
      * Sets the title of the item and writes to DB model if needed.
      */
-    public void setTitle(CharSequence title, ModelWriter modelWriter) {
+    public void setTitle(@Nullable final CharSequence title,
+            @Nullable final ModelWriter modelWriter) {
         this.title = title;
     }
 }
diff --git a/src/com/android/launcher3/model/data/LauncherAppWidgetInfo.java b/src/com/android/launcher3/model/data/LauncherAppWidgetInfo.java
index e57a895..1fbe04f 100644
--- a/src/com/android/launcher3/model/data/LauncherAppWidgetInfo.java
+++ b/src/com/android/launcher3/model/data/LauncherAppWidgetInfo.java
@@ -29,6 +29,7 @@
 import android.content.res.Resources;
 import android.os.Process;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.launcher3.Launcher;
@@ -191,7 +192,7 @@
     }
 
     @Override
-    public void onAddToDatabase(ContentWriter writer) {
+    public void onAddToDatabase(@NonNull ContentWriter writer) {
         super.onAddToDatabase(writer);
         writer.put(LauncherSettings.Favorites.APPWIDGET_ID, appWidgetId)
                 .put(LauncherSettings.Favorites.APPWIDGET_PROVIDER, providerName.flattenToString())
@@ -283,8 +284,9 @@
         }
     }
 
+    @NonNull
     @Override
-    public LauncherAtom.ItemInfo buildProto(FolderInfo folderInfo) {
+    public LauncherAtom.ItemInfo buildProto(@Nullable FolderInfo folderInfo) {
         LauncherAtom.ItemInfo info = super.buildProto(folderInfo);
         return info.toBuilder()
                 .setWidget(info.getWidget().toBuilder().setWidgetFeatures(widgetFeatures))
diff --git a/src/com/android/launcher3/model/data/SearchActionItemInfo.java b/src/com/android/launcher3/model/data/SearchActionItemInfo.java
index e879313..04042ea 100644
--- a/src/com/android/launcher3/model/data/SearchActionItemInfo.java
+++ b/src/com/android/launcher3/model/data/SearchActionItemInfo.java
@@ -24,6 +24,7 @@
 import android.os.Process;
 import android.os.UserHandle;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.launcher3.LauncherAppState;
@@ -70,7 +71,7 @@
     }
 
     @Override
-    public void copyFrom(com.android.launcher3.model.data.ItemInfo info) {
+    public void copyFrom(@NonNull com.android.launcher3.model.data.ItemInfo info) {
         super.copyFrom(info);
         SearchActionItemInfo itemInfo = (SearchActionItemInfo) info;
         this.mFallbackPackageName = itemInfo.mFallbackPackageName;
@@ -91,6 +92,7 @@
     }
 
     @Override
+    @Nullable
     public Intent getIntent() {
         return mIntent;
     }
@@ -131,8 +133,9 @@
         return new SearchActionItemInfo(this);
     }
 
+    @NonNull
     @Override
-    public ItemInfo buildProto(FolderInfo fInfo) {
+    public ItemInfo buildProto(@Nullable FolderInfo fInfo) {
         SearchActionItem.Builder itemBuilder = SearchActionItem.newBuilder()
                 .setPackageName(mFallbackPackageName);
 
diff --git a/src/com/android/launcher3/model/data/WorkspaceItemInfo.java b/src/com/android/launcher3/model/data/WorkspaceItemInfo.java
index 2b3da33..1f16474 100644
--- a/src/com/android/launcher3/model/data/WorkspaceItemInfo.java
+++ b/src/com/android/launcher3/model/data/WorkspaceItemInfo.java
@@ -24,6 +24,7 @@
 import android.text.TextUtils;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import com.android.launcher3.LauncherSettings;
 import com.android.launcher3.LauncherSettings.Favorites;
@@ -130,7 +131,7 @@
     }
 
     @Override
-    public void onAddToDatabase(ContentWriter writer) {
+    public void onAddToDatabase(@NonNull ContentWriter writer) {
         super.onAddToDatabase(writer);
         writer.put(Favorites.TITLE, title)
                 .put(Favorites.INTENT, getIntent())
@@ -147,6 +148,7 @@
     }
 
     @Override
+    @Nullable
     public Intent getIntent() {
         return intent;
     }
diff --git a/src/com/android/launcher3/widget/PendingAddWidgetInfo.java b/src/com/android/launcher3/widget/PendingAddWidgetInfo.java
index 470a800..ccf4b2e 100644
--- a/src/com/android/launcher3/widget/PendingAddWidgetInfo.java
+++ b/src/com/android/launcher3/widget/PendingAddWidgetInfo.java
@@ -19,6 +19,9 @@
 import android.content.Context;
 import android.os.Bundle;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import com.android.launcher3.LauncherSettings;
 import com.android.launcher3.PendingAddItemInfo;
 import com.android.launcher3.logger.LauncherAtom;
@@ -66,8 +69,9 @@
         return WidgetSizes.getWidgetSizeOptions(context, componentName, spanX, spanY);
     }
 
+    @NonNull
     @Override
-    public LauncherAtom.ItemInfo buildProto(FolderInfo folderInfo) {
+    public LauncherAtom.ItemInfo buildProto(@Nullable FolderInfo folderInfo) {
         LauncherAtom.ItemInfo info = super.buildProto(folderInfo);
         return info.toBuilder()
                 .addItemAttributes(LauncherAppWidgetInfo.getAttribute(sourceContainer))