1 files changed, 1 insertions, 1 deletions
diff --git a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
index d9381135..37d64633 100644
--- a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -715,7 +715,7 @@ public final class UnknownFieldSet implements MessageLite {
    * @see UnknownFieldSet
    */
   public static final class Field {
-    Field() {}
+    private Field() {}
 
     /** Construct a new {@link Builder}. */
     public static Builder newBuilder() {