OpenShift Explorer: dont do any remoting (or any long running tasks) in Action#validate

The OpenShift Explorer was developed using jface actions (we'll replace those with commands when the workload is lower). In those actions a base class offers #validate to execute basic enablement tasks etc.
#validate is executed whenever a context-menu - that contains those actions - is about to pop up. Thus #validate should not do any long running tasks since they would potentially block the UI.

example of bad code:

Another issue is the validation in the various Actions of the OpenShift Explorer. The above stack-trace shows that the error is caused by DeleteDomainAction#validate:

at org.jboss.tools.openshift.express.internal.ui.action.DeleteDomainAction.validate(DeleteDomainAction.java:47)

 
@Override
public void validate() {
	boolean enable = false;
	final Connection connection = UIUtils.getFirstElement(getSelection(), Connection.class);
	if (connection != null) {
		if (connection.isConnected()) {
			try {
				if (connection.getDefaultDomain() != null) {
					enable = true;
				}
			} catch (OpenShiftException e) {
				Logger.warn("Failed to retrieve User domain, prompting for creation", e);
			}
		}
	}
	setEnabled(enable);
}

Validate should not do long-running taks, should not do remoting like the one here.
We should review all actions to NOT do remoting (above: connection.getDefaultDomain()). They should all fail lenient:
Stay enabled even though eventually not possible (ex. there's no domain) and fail when executed: "no domain present, cannot delete".