One-line addition: `.bool => Jni.CallBooleanMethod`. The lazy-cache
+ dispatch from 1.17 handles the rest. JNI's `jboolean` is i8 in the
C ABI but always carries 0 or 1; LLVM's call boundary truncates the
return byte to i1 and the sx-level bool reads the low bit
canonically.
IR snapshot updated: `ret i1 undef` replaced by the full sequence
through vtable slot 37 keyed on `("isShown", "()Z")`.