fix test failures on main branch

Signed-off-by: zane-neo <zaniu@amazon.com>

Author: zane-neo

src/test/java/org/opensearch/neuralsearch/processor/TextChunkingProcessorTests.java

@@ -19,6 +19,7 @@
 import static java.util.Collections.singletonMap;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.when;
 import static org.mockito.Mockito.mock;
 
@@ -97,6 +98,7 @@ public void setup() {
         IndexMetadata indexMetadata = mock(IndexMetadata.class);
         when(indexMetadata.getIndex()).thenReturn(new Index("my_index", UUID.randomUUID().toString()));
         when(indexMetadata.getSettings()).thenReturn(settings);
+        when(indexMetadata.getCustomData(eq(IndexMetadata.REMOTE_STORE_CUSTOM_KEY))).thenReturn(null);
         IndexService indexService = mock(IndexService.class);
         when(indicesService.indexServiceSafe(any(Index.class))).thenReturn(indexService);
         IndexSettings indexSettings = new IndexSettings(indexMetadata, settings);