Remove superfluous BuildEventId Java class. The protobuf is just as good, and it reduces complexity to not have these wrapper classes floating around.

Probably will have no noticeable effect on performance/memory, but can't hurt.

PiperOrigin-RevId: 304197948
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BuildMetadataEvent.java b/src/main/java/com/google/devtools/build/lib/runtime/BuildMetadataEvent.java
index 542e76c..099571f 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BuildMetadataEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BuildMetadataEvent.java
@@ -16,8 +16,9 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.buildeventstream.BuildEventContext;
-import com.google.devtools.build.lib.buildeventstream.BuildEventId;
+import com.google.devtools.build.lib.buildeventstream.BuildEventIdUtil;
 import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos;
+import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos.BuildEventId;
 import com.google.devtools.build.lib.buildeventstream.BuildEventWithOrderConstraint;
 import com.google.devtools.build.lib.buildeventstream.GenericBuildEvent;
 import java.util.Collection;
@@ -42,7 +43,7 @@
 
   @Override
   public BuildEventId getEventId() {
-    return BuildEventId.buildMetadataId();
+    return BuildEventIdUtil.buildMetadataId();
   }
 
   @Override
@@ -62,6 +63,6 @@
 
   @Override
   public Collection<BuildEventId> postedAfter() {
-    return ImmutableList.of(BuildEventId.buildStartedId());
+    return ImmutableList.of(BuildEventIdUtil.buildStartedId());
   }
 }