newby: trouble installing KnowRob on ubuntu 18.04/ROS melodic

edit

Hello,

I am trying to get KnowRob to work, installing it in a VM (VirtualBox) with Ubuntu 18.04 / ROS melodic. I essentially followed following steps:

1. installed Ubuntu 18.04
2. installed java default (which is 10.0.2)
3. installed swi prolog
4. installed ROS melodic
5. installed / made catkin_ws
6. followed instructions to of developers setup ( http://knowrob.org/installation/catkin )

However when submitting the final command: catkin_make

I got the following list of errors:

-- Could NOT find rosjava_build_tools (missing: rosjava_build_tools_DIR)
-- Could not find the required component 'rosjava_build_tools'. The following CMake error indicates that you either need to install the package with the same name or change your environment so that it can be found.
CMake Error at /opt/ros/melodic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
  Could not find a package configuration file provided by
  "rosjava_build_tools" with any of the following names:

    rosjava_build_toolsConfig.cmake
    rosjava_build_tools-config.cmake

  Add the installation prefix of "rosjava_build_tools" to CMAKE_PREFIX_PATH
  or set "rosjava_build_tools_DIR" to a directory containing one of the above
  files.  If "rosjava_build_tools" provides a separate development package or
  SDK, be sure it has been installed.
Call Stack (most recent call first):
  knowrob/knowrob_common/CMakeLists.txt:6 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/dani/catkin_ws/build/CMakeFiles/CMakeOutput.log".
See also "/home/dani/catkin_ws/build/CMakeFiles/CMakeError.log".
Makefile:320: recipe for target 'cmake_check_build_system' failed
make: *** [cmake_check_build_system] Error 1
Invoking "make cmake_check_build_system" failed

Naturally, when then trying to run rosrun rosprolog rosprolog knowrob_common (after setting java envirionment vars), i got a wealth of other errors such as:

ERROR: /home/dani/catkin_ws/src/knowrob/rosprolog/prolog/roscpp.pl:48:
    /home/dani/catkin_ws/src/knowrob/rosprolog/prolog/roscpp.pl:48: Initialization goal raised exception:
    '$open_shared_object'/3: librosprolog.so: cannot open shared object file: No such file or directory
ERROR: /home/dani/catkin_ws/src/knowrob/rosprolog/prolog/roscpp.pl:49:
    catch/3: Undefined procedure: roscpp:ros_init/0

Any suggestions how to fix this would be much appreciated,

Dan