Wrong at lower case & upper case transforming

[XZ175411]

While I’ve got nesting message in my proto file, it always generates wrong class name (wrong at lower case & upper case transforming). This bothers me a lot. Could someone please help me with this?
here’s my pb-msg:

message DBRemind {
    message db_character_remind{
        string system = 1;
        uint32 value = 2;
    }
    repeated db_character_remind data = 1;
}

and I got this py file