https://docs.oracle.com/javase/specs/
https://docs.oracle.com/javase/specs/jls/se11/html/index.html
    https://docs.oracle.com/javase/specs/jls/se11/jls11.pdf
https://docs.oracle.com/javase/specs/jvms/se11/html/index.html
    https://docs.oracle.com/javase/specs/jvms/se11/jvms11.pdf