PublishEventListener: Inject PluginConfigFactory via constructor

Instead of annotating the member as @Inject, initialize the member
in a constructor that is annotated. This is a preparatory step for
implementing tests in PublishEventListenerTest, since it allows the
class to be constructed with a mock PluginConfigFactory.

Change-Id: I098d1d0687e38d7ce6320fb0076bba6964f938d1
diff --git a/src/main/java/com/cisco/gerrit/plugins/slack/PublishEventListener.java b/src/main/java/com/cisco/gerrit/plugins/slack/PublishEventListener.java
index f366d8a..6fa6007 100644
--- a/src/main/java/com/cisco/gerrit/plugins/slack/PublishEventListener.java
+++ b/src/main/java/com/cisco/gerrit/plugins/slack/PublishEventListener.java
@@ -42,7 +42,12 @@
 
   private static final String ALL_PROJECTS = "All-Projects";
 
-  @Inject private PluginConfigFactory configFactory;
+  private final PluginConfigFactory configFactory;
+
+  @Inject
+  PublishEventListener(PluginConfigFactory configFactory) {
+    this.configFactory = configFactory;
+  }
 
   @Override
   public void onEvent(Event event) {
diff --git a/src/test/java/com/cisco/gerrit/plugins/slack/PublishEventListenerTest.java b/src/test/java/com/cisco/gerrit/plugins/slack/PublishEventListenerTest.java
index 3729708..229f3ef 100644
--- a/src/test/java/com/cisco/gerrit/plugins/slack/PublishEventListenerTest.java
+++ b/src/test/java/com/cisco/gerrit/plugins/slack/PublishEventListenerTest.java
@@ -20,6 +20,7 @@
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 
+import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.gerrit.server.events.ChangeMergedEvent;
 import com.google.gerrit.server.events.PatchSetCreatedEvent;
 import org.junit.Before;
@@ -28,12 +29,13 @@
 public class PublishEventListenerTest {
   private PatchSetCreatedEvent mockPatchSetCreatedEvent = mock(PatchSetCreatedEvent.class);
   private ChangeMergedEvent mockChangeMergedEvent = mock(ChangeMergedEvent.class);
+  private PluginConfigFactory mockConfigFactory = mock(PluginConfigFactory.class);
 
   private PublishEventListener publishEventListener;
 
   @Before
   public void setup() throws Exception {
-    publishEventListener = new PublishEventListener();
+    publishEventListener = new PublishEventListener(mockConfigFactory);
   }
 
   @Test