[Mainline] Migrate TextUtils#emptyIfNull

Bug: 177477620
Test: mma
Change-Id: I0be23ae486e86864d7b3225c68ef2cfe7c7247af
diff --git a/services/core/java/com/android/server/connectivity/NetworkDiagnostics.java b/services/core/java/com/android/server/connectivity/NetworkDiagnostics.java
index a7be657..5e6b9f3 100644
--- a/services/core/java/com/android/server/connectivity/NetworkDiagnostics.java
+++ b/services/core/java/com/android/server/connectivity/NetworkDiagnostics.java
@@ -686,7 +686,7 @@
 
             mHostname = hostname;
             mMeasurement.description = "DNS TLS dst{" + mTarget.getHostAddress() + "} hostname{"
-                    + TextUtils.emptyIfNull(mHostname) + "}";
+                    + (mHostname == null ? "" : mHostname) + "}";
         }
 
         private SSLSocket setupSSLSocket() throws IOException {