Adding a component to FleetConfig follows an established pattern: the
record grows by one arg, and a back-compat constructor is added at the
OLD arity so existing callers keep compiling. That back-compat
constructor also silently captures withDefaults()'s own literal-arity
'return new FleetConfig(...)' call the next time this happens, since
that call is now a legal overload match too. It compiles, every other
test passes, and the new component is defaulted away on every load().
This is not hypothetical - it happened live while building the (now
parked) idle-sleep-guard PR, caught only because that branch's own new
tests asserted on the new field.
Add a reflective test that builds a FleetConfig through the true
canonical constructor (resolved by record-component types, not arg
count - the same pattern ConfigRefTopLevelReportingCoverageTest already
uses in this file) with a real, non-null value in every component, runs
the real withDefaults(), and asserts every value survives unchanged.
Never hardcodes the arity - it enumerates
FleetConfig.class.getRecordComponents() - so it keeps working as the
record grows. No back-compat constructor is touched or removed.
Dai Ha
dbf6fef0e9