1 files changed, 3 insertions, 1 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
index 0ff628e165..ba3608035a 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
@@ -38,6 +38,8 @@ import javax.annotation.Nullable;
  * performs a number of checks and associates the {@link Rule} and the owning {@link Package}
  * with each other.
  *
+ * <p>This class is immutable, once created the set of managed {@link RuleClass}es will not change.
+ *
  * <p>Note: the code that actually populates the RuleClass map has been moved to {@link
  * RuleClassProvider}.
  */
@@ -338,7 +340,7 @@ public class RuleFactory {
     FuncallExpression generator = topCall.first;
     BaseFunction function = topCall.second;
     String name = generator.getNameArg();
-    
+
     ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder();
     for (Map.Entry<String, Object> attributeAccessor : args.getAttributeAccessors()) {
       String attributeName = args.getName(attributeAccessor);