third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs

 #region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
@@ skipping 79 matching lines @@
                 ContainingOneof = parent.Oneofs[proto.OneofIndex];
             }
 
             file.DescriptorPool.AddSymbol(this);
             // We can't create the accessor until we've cross-linked, unfortunately, as we
             // may not know whether the type of the field is a map or not. Remember the property name
             // for later.
             // We could trust the generated code and check whether the type of the property is
             // a MapField, but that feels a tad nasty.
             this.propertyName = propertyName;
-            JsonName =  Proto.JsonName == "" ? JsonFormatter.ToCamelCase(Proto.Name) : Proto.JsonName;
+            JsonName =  Proto.JsonName == "" ? JsonFormatter.ToJsonName(Proto.Name) : Proto.JsonName;
         }
     
 
         /// <summary>
         /// The brief name of the descriptor's target.
         /// </summary>
         public override string Name => Proto.Name;
 
         /// <summary>
         /// Returns the accessor for this field.
@@ skipping 223 matching lines @@
             if (property == null)
             {
                 throw new DescriptorValidationException(this, $"Property {propertyName} not found in {ContainingType.ClrType}");
             }
             return IsMap ? new MapFieldAccessor(property, this)
                 : IsRepeated ? new RepeatedFieldAccessor(property, this)
                 : (IFieldAccessor) new SingleFieldAccessor(property, this);
         }
     }
 }