src/vs/workbench/contrib/terminal/browser/terminalGroup.ts/TerminalGroup/getLayoutInfo
class TerminalGroup:	getLayoutInfo(isActive: boolean): ITerminalTabLayoutInfoById {
		const instances = this.terminalInstances.filter(instance => typeof instance.persistentProcessId === 'number' && instance.shouldPersist);
		return {
			isActive: isActive,
			activePersistentProcessId: this.activeInstance ? this.activeInstance.persistentProcessId : undefined,
			terminals: instances.map(t => {
				return {
					relativeSize: this._splitPaneContainer?.getRelativePaneSize(t) || 0,
					terminal: t.persistentProcessId || 0
				};
			})
		};
	}