Fix a very stale comment.  ActionInput doesn't expose digest (although
it might be handy if it did).

RELNOTES: None.
PiperOrigin-RevId: 209833155
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionInput.java b/src/main/java/com/google/devtools/build/lib/actions/ActionInput.java
index 91bfb0c..0eb1853 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionInput.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionInput.java
@@ -17,8 +17,7 @@
 import com.google.devtools.build.lib.vfs.PathFragment;
 
 /**
- * Represents an input file to a build action, with an appropriate relative path and digest
- * value.
+ * Represents an input file to a build action, with an appropriate relative path.
  *
  * <p>Artifact is the only notable implementer of the interface, but the interface remains
  * because 1) some Google specific rules ship files that could be Artifacts to remote execution