[protobuf] How to convert message to its extend message?

Hello, 1. message Foo's definition, message Foo { extensions 100 to 199; } 2. extension message Baz's definition, message Baz { extend Foo { optional Baz foo_ext = 124; } } 3. get the baz object's pointer by foo object use the MutableExtension() API, Foo foo; Baz* baz = foo.MutableExt

[protobuf] How to convert message to it's extend message?

Hello, 1. message Foo's definition, message Foo { extensions 100 to 199; } 2. extension message Baz's definition, message Baz { extend Foo { optional Baz foo_ext = 124; } } 3. get the baz object's pointer by foo object use the MutableExtension() API, Foo foo; Baz* baz = foo.MutableExt