multi：true表示angular4中的提供者

我在angular4中使用http_INTERCEPTORs.为此,我创建了httpserviceInterceptor类,它实现了httpInterceptor接口并为拦截方法提供了定义.然后像这样注册http_INTERCEPTORS的提供者

providers: [{
    provide: http_INTERCEPTORS,useClass: httpserviceInterceptor,multi: true
}],

这工作正常.但我仍然不明白多重：真正意味着什么？我看过this answer.

如果我@L_470_4@multi：true选项,那么浏览器端会出现错误

Uncaught Error: Provider parse errors:
mixing multi and non multi provider is not possible for token InjectionToken_http_INTERCEPTORS ("[ERROR ->]"): in NgModule AppModule in ./AppModule@-1:-1
    at NgModuleProviderAnalyzer.webpackJsonp.487.NgModuleProviderAnalyzer.parse (vendor.js:36335)
    at NgModuleCompiler.webpackJsonp.487.NgModuleCompiler.compile (vendor.js:43184)
    at JitCompiler.webpackJsonp.487.JitCompiler._compileModule (vendor.js:51527)
    at vendor.js:51472
    at Object.then (vendor.js:26354)
    at JitCompiler.webpackJsonp.487.JitCompiler._compileModuleAndComponents (vendor.js:51470)
    at JitCompiler.webpackJsonp.487.JitCompiler.compileModuleAsync (vendor.js:51399)
    at PlatformRef_.webpackJsonp.0.PlatformRef_._bootstrapModuleWithZone (vendor.js:4746)
    at PlatformRef_.webpackJsonp.0.PlatformRef_.bootstrapModule (vendor.js:4732)
    at Object.<anonymous> (app.js:23366)

这是否意味着http_INTERCEPTORS是多提供程序,初始化多个指令或组件？如果是,那么其他指令和组件是什么？

providers: [
  { provide: FOO,useClass: Bar,multi: true },{ provide: FOO,useClass: Baz,multi: true }
]

providers: [
  { provide: FOO,useValue: [Bar,Baz] }
]