1 files changed, 21 insertions, 29 deletions
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
index b73930b2..6ad31a50 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
@@ -25,11 +25,11 @@ namespace Google.Protobuf.WellKnownTypes {
       byte[] descriptorData = global::System.Convert.FromBase64String(
           string.Concat(
             "CiBnb29nbGUvcHJvdG9idWYvZmllbGRfbWFzay5wcm90bxIPZ29vZ2xlLnBy",
-            "b3RvYnVmIhoKCUZpZWxkTWFzaxINCgVwYXRocxgBIAMoCUKJAQoTY29tLmdv",
+            "b3RvYnVmIhoKCUZpZWxkTWFzaxINCgVwYXRocxgBIAMoCUKMAQoTY29tLmdv",
             "b2dsZS5wcm90b2J1ZkIORmllbGRNYXNrUHJvdG9QAVo5Z29vZ2xlLmdvbGFu",
             "Zy5vcmcvZ2VucHJvdG8vcHJvdG9idWYvZmllbGRfbWFzaztmaWVsZF9tYXNr",
-            "ogIDR1BCqgIeR29vZ2xlLlByb3RvYnVmLldlbGxLbm93blR5cGVzYgZwcm90",
-            "bzM="));
+            "+AEBogIDR1BCqgIeR29vZ2xlLlByb3RvYnVmLldlbGxLbm93blR5cGVzYgZw",
+            "cm90bzM="));
       descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedClrTypeInfo(null, new pbr::GeneratedClrTypeInfo[] {
@@ -108,57 +108,49 @@ namespace Google.Protobuf.WellKnownTypes {
   /// describe the updated values, the API ignores the values of all
   /// fields not covered by the mask.
   ///
-  /// If a repeated field is specified for an update operation, the existing
-  /// repeated values in the target resource will be overwritten by the new values.
-  /// Note that a repeated field is only allowed in the last position of a `paths`
-  /// string.
+  /// If a repeated field is specified for an update operation, new values will
+  /// be appended to the existing repeated field in the target resource. Note that
+  /// a repeated field is only allowed in the last position of a `paths` string.
   ///
   /// If a sub-message is specified in the last position of the field mask for an
-  /// update operation, then the existing sub-message in the target resource is
-  /// overwritten. Given the target message:
+  /// update operation, then new value will be merged into the existing sub-message
+  /// in the target resource.
+  ///
+  /// For example, given the target message:
   ///
   ///     f {
   ///       b {
-  ///         d : 1
-  ///         x : 2
+  ///         d: 1
+  ///         x: 2
   ///       }
-  ///       c : 1
+  ///       c: [1]
   ///     }
   ///
   /// And an update message:
   ///
   ///     f {
   ///       b {
-  ///         d : 10
+  ///         d: 10
   ///       }
+  ///       c: [2]
   ///     }
   ///
   /// then if the field mask is:
   ///
-  ///  paths: "f.b"
+  ///  paths: ["f.b", "f.c"]
   ///
   /// then the result will be:
   ///
   ///     f {
   ///       b {
-  ///         d : 10
+  ///         d: 10
+  ///         x: 2
   ///       }
-  ///       c : 1
+  ///       c: [1, 2]
   ///     }
   ///
-  /// However, if the update mask was:
-  ///
-  ///  paths: "f.b.d"
-  ///
-  /// then the result would be:
-  ///
-  ///     f {
-  ///       b {
-  ///         d : 10
-  ///         x : 2
-  ///       }
-  ///       c : 1
-  ///     }
+  /// An implementation may provide options to override this default behavior for
+  /// repeated and message fields.
   ///
   /// In order to reset a field's value to the default, the field must
   /// be in the mask and set to the default value in the provided resource.