warning: required fields are deprecated
  --> testdata/extend/required.proto:11:5
   |
11 |     required string color = 100;
   |     ^^^^^^^^
   = help: do not attempt to change this to `optional` if the field is already
           in-use; doing so is a wire protocol break

error: message extension cannot be required
  --> testdata/extend/required.proto:11:5
   |
11 |     required string color = 100;
   |     ^^^^^^^^
   = help: extensions cannot use the `required` label

encountered 1 error and 1 warning
