How to use the @pnp/spfx-property-controls/lib/PropertyFieldCollectionData.CustomCollectionFieldType.url function in @pnp/spfx-property-controls

onChanged: (fieldValue) => onUpdate(field.id, fieldValue),
                                            strings: {
                                                cancelButtonText: strings.CancelButtonText,
                                                dialogButtonText: strings.DialogButtonText,
                                                dialogTitle: strings.DialogTitle,
                                                saveButtonText: strings.SaveButtonText
                                            }
                                        })
                                    )
                                );
                            }
                        },
                        {
                            id: 'externalTemplateUrl',
                            title: strings.ResultTypes.ExternalUrlLabel,
                            type: CustomCollectionFieldType.url,
                            onGetErrorMessage: this._onTemplateUrlChange.bind(this),
                            placeholder: 'https://mysite/Documents/external.html'
                        },
                    ]
                })
            );
        }
        // Only show the template external URL for 'Custom' option
        if (this.properties.selectedLayout === ResultsLayoutOption.Custom) {
            stylingFields.splice(6, 0, PropertyPaneTextField('externalTemplateUrl', {
                label: strings.TemplateUrlFieldLabel,
                placeholder: strings.TemplateUrlPlaceholder,
                deferredValidationTime: 500,
                onGetErrorMessage: this._onTemplateUrlChange.bind(this)
            }));
        }