Method constructor

packages/examples/core/di/ts/metadata_spec.ts:151–156

(@Optional() @Host() os: OtherService, @Optional() @Host() hs: HostService)

          logs: string[] = [];

          constructor(@Optional() @Host() os: OtherService, @Optional() @Host() hs: HostService) {
            // os is null: true
            this.logs.push(`os is null: ${os === null}`);
            // hs is an instance of HostService: true
            this.logs.push(`hs is an instance of HostService: ${hs instanceof HostService}`);
          }
        }

        @Component({