Revert "Revert "Revert "Correct nullability and final constraints on new APIs."""

This reverts commit b255be1307aeae47ca7e8ee72ab4da670a1c49f1.

Reason for revert: the commit being reverted fixed git_master but broke aosp-master. This revert is aimed to fix aosp-master while not touching git_master.

DO NOT MERGE: This change is aimed at aosp-master only and should not be merged into git_master.

Change-Id: Ie5aaabb211affe2d21daaf87809641276d9d4707
diff --git a/telecomm/java/android/telecom/TelecomManager.java b/telecomm/java/android/telecom/TelecomManager.java
index ce65cc1..c60eb56 100644
--- a/telecomm/java/android/telecom/TelecomManager.java
+++ b/telecomm/java/android/telecom/TelecomManager.java
@@ -17,7 +17,6 @@
 import android.Manifest;
 import android.annotation.IntDef;
 import android.annotation.NonNull;
-import android.annotation.Nullable;
 import android.annotation.RequiresPermission;
 import android.annotation.SuppressAutoDoc;
 import android.annotation.SuppressLint;
@@ -805,11 +804,10 @@
      * <p>
      * The default dialer has access to use this method.
      *
-     * @return The user outgoing phone account selected by the user, or {@code null} if there is no
-     * user selected outgoing {@link PhoneAccountHandle}.
+     * @return The user outgoing phone account selected by the user.
      */
     @RequiresPermission(android.Manifest.permission.READ_PHONE_STATE)
-    public @Nullable PhoneAccountHandle getUserSelectedOutgoingPhoneAccount() {
+    public PhoneAccountHandle getUserSelectedOutgoingPhoneAccount() {
         try {
             if (isServiceConnected()) {
                 return getTelecomService().getUserSelectedOutgoingPhoneAccount(
@@ -825,13 +823,12 @@
      * Sets the user-chosen default {@link PhoneAccountHandle} for making outgoing phone calls.
      *
      * @param accountHandle The {@link PhoneAccountHandle} which will be used by default for making
-     *                      outgoing voice calls, or {@code null} if no default is specified (the
-     *                      user will be asked each time a call is placed in this case).
+     *                      outgoing voice calls.
      * @hide
      */
     @RequiresPermission(android.Manifest.permission.MODIFY_PHONE_STATE)
     @SystemApi
-    public void setUserSelectedOutgoingPhoneAccount(@Nullable PhoneAccountHandle accountHandle) {
+    public void setUserSelectedOutgoingPhoneAccount(PhoneAccountHandle accountHandle) {
         try {
             if (isServiceConnected()) {
                 getTelecomService().setUserSelectedOutgoingPhoneAccount(accountHandle);
@@ -1198,8 +1195,7 @@
     /**
      * Used to set the default dialer package.
      *
-     * @param packageName to set the default dialer to, or {@code null} if the system provided
-     *                    dialer should be used instead.
+     * @param packageName to set the default dialer to.
      *
      * @result {@code true} if the default dialer was successfully changed, {@code false} if
      *         the specified package does not correspond to an installed dialer, or is already
@@ -1216,7 +1212,7 @@
     @RequiresPermission(allOf = {
             android.Manifest.permission.MODIFY_PHONE_STATE,
             android.Manifest.permission.WRITE_SECURE_SETTINGS})
-    public boolean setDefaultDialer(@Nullable String packageName) {
+    public boolean setDefaultDialer(String packageName) {
         try {
             if (isServiceConnected()) {
                 return getTelecomService().setDefaultDialer(packageName);
@@ -1230,10 +1226,9 @@
     /**
      * Determines the package name of the system-provided default phone app.
      *
-     * @return package name for the system dialer package or {@code null} if no system dialer is
-     *         preloaded.
+     * @return package name for the system dialer package or null if no system dialer is preloaded.
      */
-    public @Nullable String getSystemDialerPackage() {
+    public String getSystemDialerPackage() {
         try {
             if (isServiceConnected()) {
                 return getTelecomService().getSystemDialerPackage();