LittleProxy-parent is a container to build the Man-In-The-Middle extension in conjunction with a patched version of LittleProxy with additional offline features enabled. It's not longer needed to build the master branch of ganskef/LittleProxy-mitm.
Use the enable_offline_caching_with_mitm branches of LittleProxy and LittleProxy-mitm with the following commands:
$ git clone git://github.com/ganskef/LittleProxy-parent.git --recurse-submodules
$ cd LittleProxy-parent
$ mvn clean install
$ cd LittleProxy-mitm/target
$ java -jar littleproxy-mitm-1.1.1-offline-shade.jar
$ curl -k -x localhost:9090 https://www.google.com/humans.txt
Please refer to the documentation of LittleProxy and LittleProxy-mitm.