FULL PRODUCT VERSION :
openjdk version "17-ea" 2021-09-14
OpenJDK Runtime Environment (build 17-ea+13-1000)
OpenJDK 64-Bit Server VM (build 17-ea+13-1000, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
macOS Catalina or BigSur Japanese

A DESCRIPTION OF THE PROBLEM :
If Input Method is activated on JPasswordField, unexpected behaviors occur intermittently.
- Crash
- Exception was thrown
    "Apple AWT Internal Exception: java.lang.NullPointerException"

This scenario is unusual, but I'd like to avoid crash.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
0. Add Japanese Input Method to OS
1. Launch sample JPasswordField dialog
2. Activate Japanese Input Method
3. Type some keys

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected:
Typed keys were input.

Actual:
Crash or exception thrown or normal(keys were input)

REPRODUCIBILITY :
Intermittent

---------- BEGIN SOURCE ----------
import javax.swing.*;
public class JPasswordFieldTest {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Swing JPasswordField component");
        JPasswordField passwordField = new JPasswordField();
        frame.add(passwordField);
        frame.setSize(200, 50);
        frame.setVisible(true);
    }
}
---------- END SOURCE ----------