syntax = "proto3"; import public "other.proto"; option java_package = "com.example.foo"; enum EnumAllowingAlias { option allow_alias = true; ENUM_ALLOWING_ALIAS_ALLOWING_UNSPECIFIED = 0; ENUM_ALLOWING_ALIAS_STARTED = 1; ENUM_ALLOWING_ALIAS_RUNNING = 2 [(custom_option) = "hello world"]; } message Outer { option (my_option).a = true; message Inner { // Level 2 int64 ival = 1; } inner inner_message = 2; EnumAllowingAlias enum_field =3; map my_map = 4; }