build geogeobra source code error missing Parser class
i download geogebra source code from https://github.com/geogebra...
but i got building errors as shown on the picture. I tried both OpenJDK8 and OpenJDK11.
I see "Problem 14: After accidental removal of Parser.java, Eclipse does not regenerate it from the .jj sources" from https://dev.geogebra.org/tr... , but i don't understand very well. such as what does .jj source means?
there is a class Parser defined in tools.jar in JDK, but it is an abstract class. So, i wonder where is this missing Parser class defined?