This bug can be seen if you run "draw9patch" of Android SDK even if you installed default-jdk & libawk-wrapper-java. By following a thread [1] on Ask Ubuntu I successfully run "draw9patch". The workaround is:
Uncomment ``` assistive_technologies=org.GNOME.Accessibility.AtkWrapper``` in file </etc/java-8-openjdk/accessibility.properties>. I'm not sure if this is a bug of openjdk-8-jre, but it is surely a bug. [1]: https://askubuntu.com/questions/695560/assistive-technology-not-found-error-while-building-aprof-plot
