Consider the example:

myconf.conf

simple-test {
  description = "Nothing will be included"
  include "lib/common"
}

lib/common.conf

common-value = 42

Doing a hocon.ParseResource("myconf.conf") results in an output of so:

{
  simple-test: {
    description: Nothing will be included
  }
}

It is not including lib/common.conf which breaks a feature of Lightbend's Configuration Library.
"include with no file extension includes any of .conf, .json, .properties".