If the user or password env var name is empty, then server refuses to start. The error is the following:

!ENTRY org.jboss.tools.openshift.cdk.server.core 4 0 2016-09-26 11:29:46.973
!MESSAGE Exec_tty error:Cannot run program "C:\Apps\HashiCorp\Vagrant\bin\vagrant.exe": Unknown reason
!STACK 0
java.io.IOException: Exec_tty error:Cannot run program "C:\Apps\HashiCorp\Vagrant\bin\vagrant.exe": Unknown reason
at org.eclipse.cdt.utils.spawner.Spawner.exec_pty(Spawner.java:387)
at org.eclipse.cdt.utils.spawner.Spawner.<init>(Spawner.java:99)
at org.eclipse.cdt.utils.spawner.ProcessFactory.exec(ProcessFactory.java:98)
at org.jboss.tools.openshift.cdk.server.core.internal.adapter.controllers.VagrantLaunchUtility.callProcess(VagrantLaunchUtility.java:198)
at org.jboss.tools.openshift.cdk.server.core.internal.adapter.controllers.VagrantLaunchUtility.callInteractive(VagrantLaunchUtility.java:185)
at org.jboss.tools.openshift.cdk.server.core.internal.adapter.controllers.VagrantLaunchUtility.callInteractive(VagrantLaunchUtility.java:178)
at org.jboss.tools.openshift.cdk.server.core.internal.adapter.controllers.CDKLaunchController.launch(CDKLaunchController.java:201)
at org.jboss.ide.eclipse.as.wtp.core.server.launch.ControllableServerLaunchConfiguration.launch(ControllableServerLaunchConfiguration.java:52)
at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:885)
at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:739)
at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:731)
at org.eclipse.wst.server.core.internal.Server.startImpl2(Server.java:3556)
at org.eclipse.wst.server.core.internal.Server.startImpl(Server.java:3492)
at org.eclipse.wst.server.core.internal.Server$StartJob.run(Server.java:367)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)