Fixup #12494: Fix documentation

Author: sauravzg

xds/src/main/java/io/grpc/xds/internal/headermutations/HeaderMutator.java

@@ -23,8 +23,8 @@
 import java.util.logging.Logger;
 
 /**
- * The HeaderMutator class is an implementation of the HeaderMutator interface. It provides methods
- * to apply header mutations to a given set of headers based on a given set of rules.
+ * The HeaderMutator provides methods to apply header mutations to a given set of headers based on a
+ * given set of rules.
  */
 public class HeaderMutator {