Upgrade JAVA

Create PDF file of US flag:

http://pdfjet.com/net/examples/example-01.html

Compile Example_01.java file into Example_01.class at Linux box (copy PDFjet.jar into same directory)

javac -classpath .:PDFjet.jar  Example_01.java

Test it at same box:

java -classpath .:PDFjet.jar Example_01

Copy Example_01.class file into Openwrt:

jamvm -classpath .:PDFjet.jar Example_01

Example_01.pdf is here:

https://www.dropbox.com/s/ilcxfz9i90z3j54/Example_01.pdf?dl=0