Following the instructions in the README, downloaded the motif headers from www.openbsd.org (openmotif-2.1.30.5p1.tgz) and set the ALT_MOTIF_DIR to this location.
Building OpenJDK build 11 on Ubuntu 7.04 fails with X11/Print.h not found.
Here is the complete log file:
/net/jsqalab/export/openjdk-bin/ubuntu/7.04/b11/build11-motif-external.log

For the build to succeed we need another package x11proto-print-dev that is not
listed in the README. We need to either add this package name to the README or
use another motif package..