FULL PRODUCT VERSION :
openjdk version "14-ea" 2020-03-17
OpenJDK Runtime Environment (build 14-ea+27-1339)
OpenJDK 64-Bit Server VM (build 14-ea+27-1339, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
macOS Catalina 10.15.3

A DESCRIPTION OF THE PROBLEM :
Traditional Chinese Cangjie Input Method has the capabiilty of 2nd candidate selection window.
Java cannot handle that window, inputting key directly affected to the original component, not the 2nd selection window.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. java JTextAreaTest.java
2. Turn on Traditional Chinese Cangjie Input Method (Screen shot: CangjileSetting.png)
3. Type "mmm", then candidate characters are displayed. (Screen shot: step1.png)
4. Type "1", then one Chinese character was input. (Screen shot: step2.png)
    Also, 2nd candidate window was displayed.
5. Type "1"

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected behavior:
The 1st character listed the candidate window will input to the JTextArea.

Actual:
Character "1" directly input to the JTextArea. (Screen shot: step3.png)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javax.swing.*;

public class JTextAreaTest {
    public static void main(String[] args) {
        JFrame f = new JFrame();
        JTextArea area = new JTextArea();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(area);
        f.setSize(200,100);
        f.setVisible(true);
    }
}
---------- END SOURCE ----------