feat: support array as arg for CatalogBuilder.addEntityProvider and others

Allows to use e.g.

```
builder.addEntityProvider(getArrayOfProviders());
```

instead of

```
builder.addEntityProvider(...getArrayOfProviders());
```

Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

.changeset/slimy-elephants-attend.md

@@ -0,0 +1,15 @@
+---
+'@backstage/plugin-catalog-backend': minor
+---
+
+Allow array as non-spread arguments at the `CatalogBuilder`.
+
+```typescript
+builder.addEntityProvider(...getArrayOfProviders());
+```
+
+can be simplified to
+
+```typescript
+builder.addEntityProvider(getArrayOfProviders());
+```

docs/integrations/aws-s3/discovery.md

@@ -67,7 +67,7 @@ import { AwsS3EntityProvider } from '@backstage/plugin-catalog-backend-module-aw
 const builder = await CatalogBuilder.create(env);
 /** ... other processors and/or providers ... */
 builder.addEntityProvider(
-  ...AwsS3EntityProvider.fromConfig(env.config, {
+  AwsS3EntityProvider.fromConfig(env.config, {
     logger: env.logger,
     schedule: env.scheduler.createScheduledTaskRunner({
       frequency: { minutes: 30 },

docs/integrations/gerrit/discovery.md

@@ -30,7 +30,7 @@ import { Duration } from 'luxon';
 const builder = await CatalogBuilder.create(env);
 /** ... other processors and/or providers ... */
 builder.addEntityProvider(
-  ...GerritEntityProvider.fromConfig(env.config, {
+  GerritEntityProvider.fromConfig(env.config, {
     logger: env.logger,
     schedule: env.scheduler.createScheduledTaskRunner({
       frequency: { minutes: 30 },

plugins/catalog-backend/api-report.md

@@ -110,11 +110,21 @@ export class BuiltinKindsEntityProcessor implements CatalogProcessor {
 
 // @public
 export class CatalogBuilder {
-  addEntityPolicy(...policies: EntityPolicy[]): CatalogBuilder;
-  addEntityProvider(...providers: EntityProvider[]): CatalogBuilder;
+  addEntityPolicy(
+    ...policies: Array<EntityPolicy | Array<EntityPolicy>>
+  ): CatalogBuilder;
+  addEntityProvider(
+    ...providers: Array<EntityProvider | Array<EntityProvider>>
+  ): CatalogBuilder;
   // @alpha
-  addPermissionRules(...permissionRules: CatalogPermissionRule[]): void;
-  addProcessor(...processors: CatalogProcessor[]): CatalogBuilder;
+  addPermissionRules(
+    ...permissionRules: Array<
+      CatalogPermissionRule | Array<CatalogPermissionRule>
+    >
+  ): void;
+  addProcessor(
+    ...processors: Array<CatalogProcessor | Array<CatalogProcessor>>
+  ): CatalogBuilder;
   build(): Promise<{
     processingEngine: CatalogProcessingEngine;
     router: Router;

plugins/catalog-backend/src/service/CatalogBuilder.ts

@@ -172,8 +172,10 @@ export class CatalogBuilder {
    *
    * @param policies - One or more policies
    */
-  addEntityPolicy(...policies: EntityPolicy[]): CatalogBuilder {
-    this.entityPolicies.push(...policies);
+  addEntityPolicy(
+    ...policies: Array<EntityPolicy | Array<EntityPolicy>>
+  ): CatalogBuilder {
+    this.entityPolicies.push(...policies.flat());
     return this;
   }
 
@@ -268,8 +270,10 @@ export class CatalogBuilder {
    *
    * @param providers - One or more entity providers
    */
-  addEntityProvider(...providers: EntityProvider[]): CatalogBuilder {
-    this.entityProviders.push(...providers);
+  addEntityProvider(
+    ...providers: Array<EntityProvider | Array<EntityProvider>>
+  ): CatalogBuilder {
+    this.entityProviders.push(...providers.flat());
     return this;
   }
 
@@ -279,8 +283,10 @@ export class CatalogBuilder {
    *
    * @param processors - One or more processors
    */
-  addProcessor(...processors: CatalogProcessor[]): CatalogBuilder {
-    this.processors.push(...processors);
+  addProcessor(
+    ...processors: Array<CatalogProcessor | Array<CatalogProcessor>>
+  ): CatalogBuilder {
+    this.processors.push(...processors.flat());
     return this;
   }
 
@@ -341,8 +347,12 @@ export class CatalogBuilder {
    * @param permissionRules - Additional permission rules
    * @alpha
    */
-  addPermissionRules(...permissionRules: CatalogPermissionRule[]) {
-    this.permissionRules.push(...permissionRules);
+  addPermissionRules(
+    ...permissionRules: Array<
+      CatalogPermissionRule | Array<CatalogPermissionRule>
+    >
+  ) {
+    this.permissionRules.push(...permissionRules.flat());
   }
 
   /**