When we enable captcha in forms, it doesn't show up

Issue

• When we enable captcha in forms, it doesn't show up and below exception appears in the logs

  Caused by: java.lang.NullPointerException
  at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1262)
  at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:225)
  at java.desktop/sun.awt.FontConfiguration.init(FontConfiguration.java:107)
  at java.desktop/sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:719)
  at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:377)
  at java.base/java.security.AccessController.doPrivileged(Native Method)
  at java.desktop/sun.font.SunFontManager.<init>(SunFontManager.java:322)
  at java.desktop/sun.awt.FcFontManager.<init>(FcFontManager.java:35)
  at java.desktop/sun.awt.X11FontManager.<init>(X11FontManager.java:56)
  ... 105 more
  Exception in thread "http-nio-8080-exec-13" java.lang.InternalError: java.lang.reflect.InvocationTargetException
  at java.desktop/sun.font.FontManagerFactory$1.run(FontManagerFactory.java:86)
  at java.base/java.security.AccessController.doPrivileged(Native Method)
  at java.desktop/sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:74)
  at java.desktop/java.awt.Font.getFont2D(Font.java:497)
  at java.desktop/java.awt.Font$FontAccessImpl.getFont2D(Font.java:237)
  at java.desktop/sun.font.FontUtilities.getFont2D(FontUtilities.java:158)
  at java.desktop/sun.font.StandardGlyphVector.initFontData(StandardGlyphVector.java:1132)
  at java.desktop/sun.font.StandardGlyphVector.init(StandardGlyphVector.java:1121)
  at java.desktop/sun.font.StandardGlyphVector.<init>(StandardGlyphVector.java:167)
  at java.desktop/java.awt.Font.createGlyphVector(Font.java:2734)
  at nl.captcha.text.renderer.DefaultWordRenderer.render(Unknown Source)
  at nl.captcha.Captcha$Builder.addText(Unknown Source)
  at com.liferay.captcha.simplecaptcha.SimpleCaptchaImpl.getSimpleCaptcha(SimpleCaptchaImpl.java:223)
  at com.liferay.captcha.simplecaptcha.SimpleCaptchaImpl.serveImage(SimpleCaptchaImpl.java:132)
  at com.liferay.captcha.util.CaptchaUtil.serveImage(CaptchaUtil.java:92)
  at com.liferay.captcha.taglib.internal.struts.GetCaptchaImageStrutsAction.execute(GetCaptchaImageStrutsAction.java:39)

Environment

• Liferay DXP 7.4 with JDK 11.0.15

Resolution

• JDK 11 doesn't bring fontconfig, so you have to install it manually. Per example using:
  • apk add --no-cache fontconfig ttf-dejavu
  • yum install fontconfig

Additional Information

• Github issue showing several workarounds