Fix the Preconditions dependency in EthernetNetworkSpecifier.

Ethernet service related files are going to be moved into Connectivity
module. Replace the Preconditions class in the EthernetNetworkSpecifier,
either add modules-utils-preconditions static lib dependency to fix it,
however, notice that will result in the duplicate class import when
moving ethernet stuff to p/m/Connectivity.

Bug: 210586283
Test: atest FrameworksNetTests EthernetServiceTests
Change-Id: I6163699be4126ef1b95dfb87ec9a6aba2c01195a

framework-t/src/android/net/EthernetNetworkSpecifier.java

@@ -23,8 +23,6 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.text.TextUtils;
 
-import com.android.internal.util.Preconditions;
-
 import java.util.Objects;
 
 /**
@@ -47,7 +45,9 @@ public final class EthernetNetworkSpecifier extends NetworkSpecifier implements
      * @param interfaceName Name of the ethernet interface the specifier refers to.
      */
     public EthernetNetworkSpecifier(@NonNull String interfaceName) {
-        Preconditions.checkStringNotEmpty(interfaceName);
+        if (TextUtils.isEmpty(interfaceName)) {
+            throw new IllegalArgumentException();
+        }
         mInterfaceName = interfaceName;
     }