Issue is observed on Mac OS 10.12.5 with JDK 9.

Problem:
Country flags are not getting printed as images except the first 4 symbols. Remaining symbols are printed as two letter text, for example IN for Indian flag, US for United States flag.

How to get emoji symbols:
System Preferences -> Keyboard -> Show Keyboard and Characters Viewers
should be checked.

To display emoji symbols on character viewer:
Focus on TextEdit and Click the flag, then click on "Show Emoji and Symbols" on the system tray. After it shows up double click on the country flags to be displayed in the text field or text area.