json_prolog ERROR: init.pl: source_sink `library(my_lib)' does not exist

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Trying to load a library of functions from a ROS package's init.pl file, json_prolog gives the error:

ERROR: /home/path/my_package/prolog/init.pl:19:
 source_sink `library(my_lib)' does not exist 
Warning: /home/path/my_package/prolog/init.pl:19:
 Goal (directive) failed: user:use_module(library(my_lib))

The init.pl file uses the code

:- use_module(library('my_lib')).

to load a file 'my_lib.pl' located in the same directory as init.pl.

When starting the package using rosrun rosprolog rosprolog my_package the module gets compiled and loaded fine.

I suspect the problem is that JSONPrologNode.java uses ensure_loaded('/home/path/my_package/prolog/init.pl') instead of register_ros_package(my_package) which is what rosprolog uses.