Fix PreferredInterfaceType ErrorProne warnings

https://errorprone.info/bugpattern/PreferredInterfaceType

We intent to set PreferredInterfaceType to ERROR in Gerrit core.

Change-Id: I9de6ced5136561f4ac5fa5a8be05a896996f0578
Signed-off-by: Edwin Kempin <ekempin@google.com>

src/test/java/com/googlesource/gerrit/plugins/deleteproject/ProtectedProjectsTest.java

diff --git a/src/test/java/com/googlesource/gerrit/plugins/deleteproject/ProtectedProjectsTest.java b/src/test/java/com/googlesource/gerrit/plugins/deleteproject/ProtectedProjectsTest.java
index 75ea96b..045592d 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/deleteproject/ProtectedProjectsTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/deleteproject/ProtectedProjectsTest.java
@@ -26,7 +26,6 @@
 import com.google.gerrit.server.config.PluginConfig;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import java.io.File;
-import java.util.List;
 import org.eclipse.jgit.lib.Config;
 import org.junit.Before;
 import org.junit.Test;
@@ -75,7 +74,7 @@
 
   @Test
   public void customProjectIsProtected() throws Exception {
-    List<String> projects = ImmutableList.of("Custom-Parent", "^protected-.*");
+    ImmutableList<String> projects = ImmutableList.of("Custom-Parent", "^protected-.*");
     pluginConfig.setStringList("protectedProject", projects);
     when(pluginConfigFactoryMock.getFromGerritConfig(PLUGIN_NAME))
         .thenReturn(pluginConfig.asPluginConfig());