Add an enum representing the specific build file name (WORKSPACE, BUILD) to the PackageLookupValue to reduce the number of references to the filename "BUILD".

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MOS_MIGRATED_REVID=129203257
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/PackageFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/PackageFunctionTest.java
index 119205a..e243a82 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/PackageFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/PackageFunctionTest.java
@@ -51,18 +51,15 @@
 import com.google.devtools.build.skyframe.RecordingDifferencer;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
-
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-
 import java.io.IOException;
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
-
 import javax.annotation.Nullable;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 
 /**
  * Unit tests of specific functionality of PackageFunction. Note that it's already tested
@@ -102,6 +99,12 @@
   }
 
   @Test
+  public void testValidPackage() throws Exception {
+    scratch.file("pkg/BUILD");
+    validPackage(PackageValue.key(PackageIdentifier.parse("@//pkg")));
+  }
+
+  @Test
   public void testInconsistentNewPackage() throws Exception {
     scratch.file("pkg/BUILD", "subinclude('//foo:sub')");
     scratch.file("foo/sub");