public login(email: string, password: string): Observable<UserModel> {
        const cognitoUser = new CognitoUser(this.getUserData(email));
        cognitoUser.setAuthenticationFlowType('USER_PASSWORD_AUTH');
        const authenticationDetails = new AuthenticationDetails(CognitoUtils.getAuthDetails(email, password));
        const self = this;
        return Observable.create((obs: Observer<UserModel>) => {
            cognitoUser.authenticateUser(authenticationDetails, {
                onSuccess: result => {
                    this.session = result;
                    const token = result.getIdToken();
                    const accessToken = result.getAccessToken();
                    this.localStorage.setToken(token);
                    this.localStorage.setAccessToken(accessToken);
                    obs.complete();
                },
                onFailure: err => {
                    obs.error(err);
                },
                newPasswordRequired: (userAttributes, requiredAttributes) => {
                    let dialogRef: MatDialogRef<NewPasswordComponent>;
                    const config = new MatDialogConfig();;
                    config.role = 'dialog';
                    config.width = '40%';
                    config.data = { newPass: self.newPass };
                    dialogRef = self.dialog.open(NewPasswordComponent, config);

                    dialogRef.afterClosed().subscribe(result => {
                        self.newPass = result;
                        cognitoUser.completeNewPasswordChallenge(self.newPass, userAttributes, {
                            onSuccess: result => {
                                obs.complete();
                            },
                            onFailure: err => {
                                obs.error(err);
                            }
                        });
                    });
                }
            });
        });
    }

dialogRef.afterClosed().subscribe(result => {
          self.newPass = result;
          cognitoUser.completeNewPasswordChallenge(self.newPass, {"name":"John Doe"}, {
            onSuccess: result => {
              obs.complete();
            },
            onFailure: err => {
              obs.error(err);
            }
          });