To run Apex runner of Apache Beam

[Claire Yuan]

Hi,  I am using the Apex runner to execute Apache Beam example pipeline. 
However my terminal always get frozen when running the command:mvn compile 
exec:java -Dexec.mainClass=org.apache.beam.examples.TfIdf \
     -Dexec.args="--inputFile=pom.xml --output=counts --runner=ApexRunner" 
-Papex-runner  Would anyone have solution for this?
Claire