1 files changed, 6 insertions, 6 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 10daadda48..3b54a8b17c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -26,7 +26,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSortedMap;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Interner;
 import com.google.common.collect.Interners;
 import com.google.common.collect.Iterables;
@@ -1112,6 +1111,7 @@ public class BuildConfiguration implements BuildEvent {
   private final String checksum;
 
   private final ImmutableSortedMap<Class<? extends Fragment>, Fragment> fragments;
+  private final FragmentClassSet fragmentClassSet;
 
   private final ImmutableMap<String, Class<? extends Fragment>> skylarkVisibleFragments;
   private final String repositoryName;
@@ -1390,6 +1390,7 @@ public class BuildConfiguration implements BuildEvent {
       String repositoryName) {
     this.directories = directories;
     this.fragments = makeFragmentsMap(fragmentsMap);
+    this.fragmentClassSet = FragmentClassSet.of(this.fragments.keySet());
 
     this.skylarkVisibleFragments = buildIndexOfSkylarkVisibleFragments();
     this.repositoryName = repositoryName;
@@ -1475,12 +1476,11 @@ public class BuildConfiguration implements BuildEvent {
    * configuration is assumed to have).
    */
   public BuildConfiguration clone(
-      Set<Class<? extends BuildConfiguration.Fragment>> fragmentClasses,
-      RuleClassProvider ruleClassProvider) {
+      FragmentClassSet fragmentClasses, RuleClassProvider ruleClassProvider) {
 
     ClassToInstanceMap<Fragment> fragmentsMap = MutableClassToInstanceMap.create();
     for (Fragment fragment : fragments.values()) {
-      if (fragmentClasses.contains(fragment.getClass())) {
+      if (fragmentClasses.fragmentClasses().contains(fragment.getClass())) {
         fragmentsMap.put(fragment.getClass(), fragment);
       }
     }
@@ -1847,8 +1847,8 @@ public class BuildConfiguration implements BuildEvent {
   }
 
   /** Which fragments does this configuration contain? */
-  public ImmutableSortedSet<Class<? extends Fragment>> fragmentClasses() {
-    return fragments.keySet();
+  public FragmentClassSet fragmentClasses() {
+    return fragmentClassSet;
   }
 
   /**