In my experience, most such people just solve this problem by either:
1. submitting an issue to the project's issue tracker, and waiting;
2. submitting an issue to the project's issue tracker, and becoming a project sponsor to expedite;
3. customizing the software using a scripting language it exposes;
4. using a third-party "plugin" for the project that someone else already developed to solve the problem;
5. developing such a plugin yourself, using the software's C FFI API to write your plugin library in your language of choice, rather than the language the software itself is written in;
6. wrapping the software in a single-purpose gateway that decorates or mutates its wire protocol/API with the new features.
In practice, actually modifying the server software itself is very rare. Needlessly rare, even. Some great, clean codebases (Postgres itself; Nginx) get strategies #3-#6 applied so often that there exists a whole ecosystem of features "around" them that really should be in their cores, because everyone was too afraid to touch them even when they're written in common languages.
1. submitting an issue to the project's issue tracker, and waiting;
2. submitting an issue to the project's issue tracker, and becoming a project sponsor to expedite;
3. customizing the software using a scripting language it exposes;
4. using a third-party "plugin" for the project that someone else already developed to solve the problem;
5. developing such a plugin yourself, using the software's C FFI API to write your plugin library in your language of choice, rather than the language the software itself is written in;
6. wrapping the software in a single-purpose gateway that decorates or mutates its wire protocol/API with the new features.
In practice, actually modifying the server software itself is very rare. Needlessly rare, even. Some great, clean codebases (Postgres itself; Nginx) get strategies #3-#6 applied so often that there exists a whole ecosystem of features "around" them that really should be in their cores, because everyone was too afraid to touch them even when they're written in common languages.