catalog-backend: switch default stitiching mode to 'deferred'

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/clever-windows-judge.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend': major
+---
+
+**BREAKING**: The default `catalog.stitchingStrategy` has been switched to `{ mode: 'deferred' }`.

plugins/catalog-backend/config.d.ts

@@ -172,7 +172,7 @@ export interface Config {
     orphanProviderStrategy?: 'keep' | 'delete';
 
     /**
-     * The strategy to use when stitching together the final entities.
+     * The strategy to use when stitching together the final entities. The default mode is "deferred".
      */
     stitchingStrategy?:
       | {

plugins/catalog-backend/src/stitching/types.ts

@@ -61,11 +61,11 @@ export function stitchingStrategyFromConfig(config: Config): StitchingStrategy {
     'catalog.stitchingStrategy.mode',
   );
 
-  if (strategyMode === undefined || strategyMode === 'immediate') {
+  if (strategyMode === 'immediate') {
     return {
       mode: 'immediate',
     };
-  } else if (strategyMode === 'deferred') {
+  } else if (strategyMode === undefined || strategyMode === 'deferred') {
     const pollingIntervalKey = 'catalog.stitchingStrategy.pollingInterval';
     const stitchTimeoutKey = 'catalog.stitchingStrategy.stitchTimeout';