add defaultTarget to ExternalRouteRef

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

packages/frontend-plugin-api/api-report.md

@@ -573,6 +573,7 @@ export function createExternalRouteRef<
     ? (keyof TParams)[]
     : TParamKeys[];
   optional?: TOptional;
+  defaultTarget?: string;
 }): ExternalRouteRef<
   keyof TParams extends never
     ? undefined

packages/frontend-plugin-api/src/routing/ExternalRouteRef.ts

@@ -44,6 +44,7 @@ export interface InternalExternalRouteRef<
   readonly version: 'v1';
   getParams(): string[];
   getDescription(): string;
+  getDefaultTarget(): string | undefined;
 
   setId(id: string): void;
 }
@@ -80,10 +81,15 @@ class ExternalRouteRefImpl
   constructor(
     readonly optional: boolean,
     readonly params: string[] = [],
+    readonly defaultTarget: string | undefined,
     creationSite: string,
   ) {
     super(params, creationSite);
   }
+
+  getDefaultTarget() {
+    return this.defaultTarget;
+  }
 }
 
 /**
@@ -115,6 +121,14 @@ export function createExternalRouteRef<
    * if they aren't, `useExternalRouteRef` will return `undefined`.
    */
   optional?: TOptional;
+
+  /**
+   * The route (typically in another plugin) that this should map to by default.
+   *
+   * The string is expected to be on the standard `<plugin id>.<route id>` form,
+   * for example `techdocs.docRoot`.
+   */
+  defaultTarget?: string;
 }): ExternalRouteRef<
   keyof TParams extends never
     ? undefined
@@ -126,6 +140,7 @@ export function createExternalRouteRef<
   return new ExternalRouteRefImpl(
     Boolean(options?.optional),
     options?.params as string[] | undefined,
+    options?.defaultTarget,
     describeParentCallSite(),
   ) as ExternalRouteRef<any, any>;
 }