Fix Checkstyle violations in OpenSearchVectorStoreTest

Resolved 14 Checkstyle errors that blocked the build process:
- Corrected import statement ordering
- Added 'this.' qualifier to instance variable references
- Added missing newline at end of file

This ensures compliance with Spring AI coding standards and enables
successful compilation after rebasing onto upstream/main.

Signed-off-by: sanghun <vitash1215@gmail.com>

Author: lsh1215

vector-stores/spring-ai-opensearch-store/src/test/java/org/springframework/ai/vectorstore/opensearch/OpenSearchVectorStoreTest.java

@@ -16,13 +16,6 @@
 
 package org.springframework.ai.vectorstore.opensearch;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
-import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.Mockito.lenient;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
-
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
@@ -43,6 +36,13 @@
 import org.springframework.ai.document.Document;
 import org.springframework.ai.embedding.EmbeddingModel;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
 /**
  * Unit tests for OpenSearchVectorStore.doAdd() method.
  *
@@ -64,17 +64,17 @@ class OpenSearchVectorStoreTest {
 	@BeforeEach
 	void setUp() throws IOException {
 		// Use lenient to avoid UnnecessaryStubbingException
-		lenient().when(mockEmbeddingModel.dimensions()).thenReturn(3);
-		lenient().when(mockOpenSearchClient.bulk(any(BulkRequest.class))).thenReturn(mockBulkResponse);
-		lenient().when(mockBulkResponse.errors()).thenReturn(false);
+		lenient().when(this.mockEmbeddingModel.dimensions()).thenReturn(3);
+		lenient().when(this.mockOpenSearchClient.bulk(any(BulkRequest.class))).thenReturn(this.mockBulkResponse);
+		lenient().when(this.mockBulkResponse.errors()).thenReturn(false);
 	}
 
 	@ParameterizedTest(name = "manageDocumentIds={0}")
 	@ValueSource(booleans = { true, false })
 	@DisplayName("Should handle document ID management setting correctly")
 	void shouldHandleDocumentIdManagementSetting(boolean manageDocumentIds) throws IOException {
 		// Given
-		when(mockEmbeddingModel.embed(any(), any(), any()))
+		when(this.mockEmbeddingModel.embed(any(), any(), any()))
 			.thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f }, new float[] { 0.4f, 0.5f, 0.6f }));
 
 		OpenSearchVectorStore vectorStore = createVectorStore(manageDocumentIds);
@@ -95,7 +95,7 @@ void shouldHandleDocumentIdManagementSetting(boolean manageDocumentIds) throws I
 	@DisplayName("Should handle single document correctly")
 	void shouldHandleSingleDocumentCorrectly() throws IOException {
 		// Given
-		when(mockEmbeddingModel.embed(any(), any(), any())).thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f }));
+		when(this.mockEmbeddingModel.embed(any(), any(), any())).thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f }));
 
 		OpenSearchVectorStore vectorStore = createVectorStore(true);
 		Document document = new Document("test-id", "test content", Map.of("key", "value"));
@@ -116,7 +116,7 @@ void shouldHandleSingleDocumentCorrectly() throws IOException {
 	@DisplayName("Should handle multiple documents with explicit IDs")
 	void shouldHandleMultipleDocumentsWithExplicitIds() throws IOException {
 		// Given
-		when(mockEmbeddingModel.embed(any(), any(), any())).thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f },
+		when(this.mockEmbeddingModel.embed(any(), any(), any())).thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f },
 				new float[] { 0.4f, 0.5f, 0.6f }, new float[] { 0.7f, 0.8f, 0.9f }));
 
 		OpenSearchVectorStore vectorStore = createVectorStore(true);
@@ -141,7 +141,7 @@ void shouldHandleMultipleDocumentsWithExplicitIds() throws IOException {
 	@DisplayName("Should handle multiple documents without explicit IDs")
 	void shouldHandleMultipleDocumentsWithoutExplicitIds() throws IOException {
 		// Given
-		when(mockEmbeddingModel.embed(any(), any(), any()))
+		when(this.mockEmbeddingModel.embed(any(), any(), any()))
 			.thenReturn(List.of(new float[] { 0.1f, 0.2f, 0.3f }, new float[] { 0.4f, 0.5f, 0.6f }));
 
 		OpenSearchVectorStore vectorStore = createVectorStore(false);
@@ -165,7 +165,7 @@ void shouldHandleMultipleDocumentsWithoutExplicitIds() throws IOException {
 	@DisplayName("Should handle embedding model error")
 	void shouldHandleEmbeddingModelError() {
 		// Given
-		when(mockEmbeddingModel.embed(any(), any(), any())).thenThrow(new RuntimeException("Embedding failed"));
+		when(this.mockEmbeddingModel.embed(any(), any(), any())).thenThrow(new RuntimeException("Embedding failed"));
 
 		OpenSearchVectorStore vectorStore = createVectorStore(true);
 		List<Document> documents = List.of(new Document("doc1", "content", Map.of()));
@@ -178,14 +178,14 @@ void shouldHandleEmbeddingModelError() {
 	// Helper methods
 
 	private OpenSearchVectorStore createVectorStore(boolean manageDocumentIds) {
-		return OpenSearchVectorStore.builder(mockOpenSearchClient, mockEmbeddingModel)
+		return OpenSearchVectorStore.builder(this.mockOpenSearchClient, this.mockEmbeddingModel)
 			.manageDocumentIds(manageDocumentIds)
 			.build();
 	}
 
 	private BulkRequest captureBulkRequest() throws IOException {
 		ArgumentCaptor<BulkRequest> captor = ArgumentCaptor.forClass(BulkRequest.class);
-		verify(mockOpenSearchClient).bulk(captor.capture());
+		verify(this.mockOpenSearchClient).bulk(captor.capture());
 		return captor.getValue();
 	}
 
@@ -203,4 +203,4 @@ private void verifyDocumentIdHandling(BulkRequest request, boolean shouldHaveExp
 		}
 	}
 
-}
+}