9.6 ADR-6: Pluggable parser via a class name, resolved defensively

Status: accepted (0.2.3)

Context: The Antora parser is the only source-format implementation, but the interface was already there. Making it configurable turns the library into something reusable for other formats.

Decision: Configuration.parserClass holds a fully qualified class name as a String, resolved at runtime. The class is loaded without running its static initializers and is only instantiated after it has been verified to implement Parser. The thread context class loader is tried first, falling back to the library’s own.

Consequences: A typo fails the build with a clear message instead of executing unrelated code. A Class<?> parameter was rejected for two reasons: Maven’s converter resolves such a value in the Maven core class realm, which cannot see plugin-realm classes, and it initializes the class while converting — running code before any type check.