null not handled correctly for npe

[snaum]

Null pointer exception is not getting handled correctly, because npe.getMessage() is itself null.

@slf4j
public class Demo {
public static void doIt(){
Map<String, String> map = new ConcurrentHashMap<>();
try {
map.put(null, null);
} catch (NullPointerException npe) {
log.error(npe.getMessage(), npe);
}
}
}

class DemoTest extends Specification {
def "DoIt"() {
given:
TestLogger logger = TestLoggerFactory.getTestLogger(Demo.class);
Demo.doIt();
expect:
logger.getAllLoggingEvents().size() > 0;
}
}