Test reader-gtfs for public transport

I created a new folder at the desktop called dev and accessed it through the babun

I did the following procedure on Babun
step 1 - (I downloaded the latest version in git clone)
git clone https://github.com/graphhopper/graphhopper
2 - (I accessed the folder as master)
cd graphhopper
3 - (I did the installation of example gtfs and pbf)
wget -O gtfs-vbb.zip http://transitfeeds.com/p/verkehrsverbund-berlin-brandenburg/213/latest/download
wget http://download.geofabrik.de/europe/germany/brandenburg-latest.osm.pbf
4 - makes the maven’s
./graphhopper.sh build

after doing the following:

java -Xmx8g -Xms8g -Dgraphhopper.datareader.file = brandenburg-latest.osm.pbf -Dgraphhopper.gtfs.file = gtfs-vbb.zip -Dgraphhopper.graph.flag_encoders = en -Dgraphhopper.prepare.ch.weightings = no - Dgraphhopper.graph.location = / graph-cache -jar web / target / graphhopper-web- * .jar config.yml server

Returns the following error:

Error occurred during initialization of VM
Could not reserve enough space for object heap

Can someone help me? What have I done wrong or what is missing being done?