question: public static String [ ] executorCommand ( Config config , Config runtime , int containerIndex , List < Integer > freePorts ) { if ( freePorts . size ( ) < PORTS_REQUIRED_FOR_EXECUTOR ) { throw new RuntimeException ( "Failed to find enough ports for executor" ) ; } for ( int port : freePorts ) { if ( port == - 1 ) { throw new RuntimeException ( "Failed to find available ports for executor" ) ; } } List < String > ports = new LinkedList < > ( ) ; for ( int port : freePorts ) { ports . add ( Integer . toString ( port ) ) ; } return getExecutorCommand ( config , runtime , containerIndex , ports ) ; }
target:  Utils method to construct the command to start heron-executor