A hotspot test (test/hotspot/jtreg/runtime/jni/FindClassUtf8/libFindClassUtf8.c) uses an unterminated character string as the class name argument to FindClass():

    const uint64_t chars = 0x5b3132315d20f818UL; // f8 is invalid utf8

    jclass badClass = (*env)->FindClass(env, (const char*)&chars);