The problem

The generated Java source files for Protocol Buffer enums have getNumber() as accessors for the tag number in the protobuf file.

In addition, since it’s a java enum, it also has the ordinal() method, returning its positional index within the generated java enum.

The ordinal() order of the generated Java enums isn’t guaranteed, and can change when a new enum value is inserted into a proto enum. The getNumber() value won’t change for an enum value (since making that change is a backwards-incompatible change for the protocol buffer).

You should very likely use getNumber() in preference to ordinal() in all circumstances since it’s a more stable value.

Note: If you’re changing code that was already using ordinal(), it’s likely that getNumber() will return a different real value. Tread carefully to avoid mismatches if the ordinal was persisted elsewhere.

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("ProtocolBufferOrdinal") to the enclosing element.