src/vs/workbench/contrib/tasks/common/tasks.ts/CustomTask/constructor
class CustomTask:	public constructor(id: string, source: FileBasedTaskSource, label: string, type: string, command: ICommandConfiguration | undefined,
		hasDefinedMatchers: boolean, runOptions: IRunOptions, configurationProperties: IConfigurationProperties) {
		super(id, label, undefined, runOptions, configurationProperties, source);
		this._source = source;
		this.hasDefinedMatchers = hasDefinedMatchers;
		if (command) {
			this.command = command;
		}
	}