Add SplitResponseProcessor to allowlist (#15393)

Signed-off-by: Daniel Widdis <widdis@gmail.com>

Author: dbwiddis

CHANGELOG.md

@@ -67,6 +67,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fixed array field name omission in flat_object function for nested JSON ([#13620](https://github.com/opensearch-project/OpenSearch/pull/13620))
 - Fix range aggregation optimization ignoring top level queries ([#15194](https://github.com/opensearch-project/OpenSearch/pull/15194))
 - Fix incorrect parameter names in MinHash token filter configuration handling ([#15233](https://github.com/opensearch-project/OpenSearch/pull/15233))
+- Fix split response processor not included in allowlist ([#15393](https://github.com/opensearch-project/OpenSearch/pull/15393))
 
 ### Security
 

modules/search-pipeline-common/src/main/java/org/opensearch/search/pipeline/common/SearchPipelineCommonModulePlugin.java

@@ -97,6 +97,8 @@ public Map<String, Processor.Factory<SearchResponseProcessor>> getResponseProces
                 new TruncateHitsResponseProcessor.Factory(),
                 CollapseResponseProcessor.TYPE,
                 new CollapseResponseProcessor.Factory(),
+                SplitResponseProcessor.TYPE,
+                new SplitResponseProcessor.Factory(),
                 SortResponseProcessor.TYPE,
                 new SortResponseProcessor.Factory()
             )

modules/search-pipeline-common/src/test/java/org/opensearch/search/pipeline/common/SearchPipelineCommonModulePluginTests.java

@@ -47,6 +47,7 @@ public void testResponseProcessorAllowlist() throws IOException {
             List.of("rename_field", "truncate_hits", "collapse"),
             SearchPipelineCommonModulePlugin::getResponseProcessors
         );
+        runAllowlistTest(key, List.of("split", "sort"), SearchPipelineCommonModulePlugin::getResponseProcessors);
 
         final IllegalArgumentException e = expectThrows(
             IllegalArgumentException.class,
@@ -82,7 +83,7 @@ public void testAllowlistNotSpecified() throws IOException {
         try (SearchPipelineCommonModulePlugin plugin = new SearchPipelineCommonModulePlugin()) {
             assertEquals(Set.of("oversample", "filter_query", "script"), plugin.getRequestProcessors(createParameters(settings)).keySet());
             assertEquals(
-                Set.of("rename_field", "truncate_hits", "collapse", "sort"),
+                Set.of("rename_field", "truncate_hits", "collapse", "split", "sort"),
                 plugin.getResponseProcessors(createParameters(settings)).keySet()
             );
             assertEquals(Set.of(), plugin.getSearchPhaseResultsProcessors(createParameters(settings)).keySet());