| Proto builders provide a pleasant fluent interface for constructing instances. |
| Unlike argument lists, however, they do not prevent the user from providing |
| multiple values for the same field. |
| |
| Setting the same field multiple times in the same chained expression is |
| pointless (as the intermediate value will be overwritten), and certainly |
| unintentional. If the field is set to different values, it may be a bug, e.g., |
| |
| ```java |
| return MyProto.newBuilder() |
| .setFoo(copy.getFoo()) |
| .setFoo(copy.getBar()) |
| .build(); |
| ``` |
