Fix NPE when have no phone accounts

Return empty List instead of null so calling functions don't throw NPE
when dereferencing return value.

Bug:17282683
Bug:17262485
Change-Id: Ica4952b11a8af28787a4a0b6a991ab888386aa7b
diff --git a/telecomm/java/android/telecomm/RemoteConnection.java b/telecomm/java/android/telecomm/RemoteConnection.java
index 20d1574..8c86b15 100644
--- a/telecomm/java/android/telecomm/RemoteConnection.java
+++ b/telecomm/java/android/telecomm/RemoteConnection.java
@@ -298,7 +298,7 @@
      * @return The children of this {@code RemoteConnection} if this {@code RemoteConnection} is
      * a conference, or an empty {@code List} otherwise.
      */
-    public List<RemoteConnection> getChildren() { return null; }
+    public List<RemoteConnection> getChildren() { return new ArrayList<>(); }
 
     /**
      * Obtains the state of this {@code RemoteConnection}.
diff --git a/telecomm/java/android/telecomm/TelecommManager.java b/telecomm/java/android/telecomm/TelecommManager.java
index 178a25f..868282f 100644
--- a/telecomm/java/android/telecomm/TelecommManager.java
+++ b/telecomm/java/android/telecomm/TelecommManager.java
@@ -24,6 +24,7 @@
 
 import com.android.internal.telecomm.ITelecommService;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -298,7 +299,7 @@
         } catch (RemoteException e) {
             Log.e(TAG, "Error calling ITelecommService#getOutgoingPhoneAccounts", e);
         }
-        return null;
+        return new ArrayList<>();
     }
 
     /**