Refactor DefaultApiVersionInserter

spring-web/src/main/java/org/springframework/web/client/ApiVersionInserter.java

@@ -18,6 +18,8 @@ package org.springframework.web.client;
 
 import java.net.URI;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.http.HttpHeaders;
 
 /**
@@ -49,4 +51,67 @@ public interface ApiVersionInserter {
 	default void insertVersion(Object version, HttpHeaders headers) {
 	}
 
+
+	/**
+	 * Create a builder for an inserter that sets a header.
+	 * @param header the name of a header to hold the version
+	 */
+	static Builder fromHeader(@Nullable String header) {
+		return new DefaultApiVersionInserterBuilder(header, null, null);
+	}
+
+	/**
+	 * Create a builder for an inserter that sets a query parameter.
+	 * @param queryParam the name of a query parameter to hold the version
+	 */
+	static Builder fromQueryParam(@Nullable String queryParam) {
+		return new DefaultApiVersionInserterBuilder(null, queryParam, null);
+	}
+
+	/**
+	 * Create a builder for an inserter that inserts a path segment.
+	 * @param pathSegmentIndex the index of the path segment to hold the version
+	 */
+	static Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
+		return new DefaultApiVersionInserterBuilder(null, null, pathSegmentIndex);
+	}
+
+
+	/**
+	 * Builder for {@link ApiVersionInserter}.
+	 */
+	interface Builder {
+
+		/**
+		 * Configure the inserter to set a header.
+		 * @param header the name of the header to hold the version
+		 */
+		Builder fromHeader(@Nullable String header);
+
+		/**
+		 * Configure the inserter to set a query parameter.
+		 * @param queryParam the name of the query parameter to hold the version
+		 */
+		Builder fromQueryParam(@Nullable String queryParam);
+
+		/**
+		 * Configure the inserter to insert a path segment.
+		 * @param pathSegmentIndex the index of the path segment to hold the version
+		 */
+		Builder fromPathSegment(@Nullable Integer pathSegmentIndex);
+
+		/**
+		 * Format the version Object into a String using the given {@link ApiVersionFormatter}.
+		 * <p>By default, the version is formatted with {@link Object#toString()}.
+		 * @param versionFormatter the formatter to use
+		 */
+		Builder withVersionFormatter(ApiVersionFormatter versionFormatter);
+
+		/**
+		 * Build the {@link ApiVersionInserter} instance.
+		 */
+		ApiVersionInserter build();
+
+	}
+
 }

spring-web/src/main/java/org/springframework/web/client/DefaultApiVersionInserter.java

@@ -27,15 +27,13 @@ import org.springframework.util.Assert;
 import org.springframework.web.util.UriComponentsBuilder;
 
 /**
- * Default implementation of {@link ApiVersionInserter} to insert the version
+ * Default implementation of {@link ApiVersionInserter}.
- * into a request header, query parameter, or the URL path.
- *
- * <p>Use {@link #builder()} to create an instance.
  *
  * @author Rossen Stoyanchev
  * @since 7.0
+ * @see DefaultApiVersionInserterBuilder
  */
-public final class DefaultApiVersionInserter implements ApiVersionInserter {
+final class DefaultApiVersionInserter implements ApiVersionInserter {
 
 	private final @Nullable String header;
 
@@ -46,7 +44,7 @@ public final class DefaultApiVersionInserter implements ApiVersionInserter {
 	private final ApiVersionFormatter versionFormatter;
 
 
-	private DefaultApiVersionInserter(
+	DefaultApiVersionInserter(
 			@Nullable String header, @Nullable String queryParam, @Nullable Integer pathSegmentIndex,
 			@Nullable ApiVersionFormatter formatter) {
 
@@ -92,102 +90,4 @@ public final class DefaultApiVersionInserter implements ApiVersionInserter {
 		}
 	}
 
-
-	/**
-	 * Create a builder for an inserter that sets a header.
-	 * @param header the name of a header to hold the version
-	 */
-	public static Builder fromHeader(@Nullable String header) {
-		return new Builder(header, null, null);
-	}
-
-	/**
-	 * Create a builder for an inserter that sets a query parameter.
-	 * @param queryParam the name of a query parameter to hold the version
-	 */
-	public static Builder fromQueryParam(@Nullable String queryParam) {
-		return new Builder(null, queryParam, null);
-	}
-
-	/**
-	 * Create a builder for an inserter that inserts a path segment.
-	 * @param pathSegmentIndex the index of the path segment to hold the version
-	 */
-	public static Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
-		return new Builder(null, null, pathSegmentIndex);
-	}
-
-	/**
-	 * Create a builder.
-	 */
-	public static Builder builder() {
-		return new Builder(null, null, null);
-	}
-
-
-	/**
-	 * A builder for {@link DefaultApiVersionInserter}.
-	 */
-	public static final class Builder {
-
-		private @Nullable String header;
-
-		private @Nullable String queryParam;
-
-		private @Nullable Integer pathSegmentIndex;
-
-		private @Nullable ApiVersionFormatter versionFormatter;
-
-		private Builder(@Nullable String header, @Nullable String queryParam, @Nullable Integer pathSegmentIndex) {
-			this.header = header;
-			this.queryParam = queryParam;
-			this.pathSegmentIndex = pathSegmentIndex;
-		}
-
-		/**
-		 * Configure the inserter to set a header.
-		 * @param header the name of the header to hold the version
-		 */
-		public Builder fromHeader(@Nullable String header) {
-			this.header = header;
-			return this;
-		}
-
-		/**
-		 * Configure the inserter to set a query parameter.
-		 * @param queryParam the name of the query parameter to hold the version
-		 */
-		public Builder fromQueryParam(@Nullable String queryParam) {
-			this.queryParam = queryParam;
-			return this;
-		}
-
-		/**
-		 * Configure the inserter to insert a path segment.
-		 * @param pathSegmentIndex the index of the path segment to hold the version
-		 */
-		public Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
-			this.pathSegmentIndex = pathSegmentIndex;
-			return this;
-		}
-
-		/**
-		 * Format the version Object into a String using the given {@link ApiVersionFormatter}.
-		 * <p>By default, the version is formatted with {@link Object#toString()}.
-		 * @param versionFormatter the formatter to use
-		 */
-		public Builder withVersionFormatter(ApiVersionFormatter versionFormatter) {
-			this.versionFormatter = versionFormatter;
-			return this;
-		}
-
-		/**
-		 * Build the inserter.
-		 */
-		public ApiVersionInserter build() {
-			return new DefaultApiVersionInserter(
-					this.header, this.queryParam, this.pathSegmentIndex, this.versionFormatter);
-		}
-	}
-
 }

spring-web/src/main/java/org/springframework/web/client/DefaultApiVersionInserterBuilder.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2002-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client;
+
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Default implementation of {@link ApiVersionInserter.Builder}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ * @see ApiVersionInserter#fromHeader(String)
+ * @see ApiVersionInserter#fromQueryParam(String)
+ * @see ApiVersionInserter#fromPathSegment(Integer)
+ */
+final class DefaultApiVersionInserterBuilder implements ApiVersionInserter.Builder {
+
+	private @Nullable String header;
+
+	private @Nullable String queryParam;
+
+	private @Nullable Integer pathSegmentIndex;
+
+	private @Nullable ApiVersionFormatter versionFormatter;
+
+
+	DefaultApiVersionInserterBuilder(
+			@Nullable String header, @Nullable String queryParam, @Nullable Integer pathSegmentIndex) {
+
+		this.header = header;
+		this.queryParam = queryParam;
+		this.pathSegmentIndex = pathSegmentIndex;
+	}
+
+	/**
+	 * Configure the inserter to set a header.
+	 * @param header the name of the header to hold the version
+	 */
+	public ApiVersionInserter.Builder fromHeader(@Nullable String header) {
+		this.header = header;
+		return this;
+	}
+
+	/**
+	 * Configure the inserter to set a query parameter.
+	 * @param queryParam the name of the query parameter to hold the version
+	 */
+	public ApiVersionInserter.Builder fromQueryParam(@Nullable String queryParam) {
+		this.queryParam = queryParam;
+		return this;
+	}
+
+	/**
+	 * Configure the inserter to insert a path segment.
+	 * @param pathSegmentIndex the index of the path segment to hold the version
+	 */
+	public ApiVersionInserter.Builder fromPathSegment(@Nullable Integer pathSegmentIndex) {
+		this.pathSegmentIndex = pathSegmentIndex;
+		return this;
+	}
+
+	/**
+	 * Format the version Object into a String using the given {@link ApiVersionFormatter}.
+	 * <p>By default, the version is formatted with {@link Object#toString()}.
+	 * @param versionFormatter the formatter to use
+	 */
+	public ApiVersionInserter.Builder withVersionFormatter(ApiVersionFormatter versionFormatter) {
+		this.versionFormatter = versionFormatter;
+		return this;
+	}
+
+	/**
+	 * Build the inserter.
+	 */
+	public ApiVersionInserter build() {
+		return new DefaultApiVersionInserter(
+				this.header, this.queryParam, this.pathSegmentIndex, this.versionFormatter);
+	}
+
+}

spring-web/src/test/java/org/springframework/web/client/RestClientVersionTests.java

@@ -59,45 +59,45 @@ public class RestClientVersionTests {
 
 	@Test
 	void header() {
-		performRequest(DefaultApiVersionInserter.fromHeader("X-API-Version"));
+		performRequest(ApiVersionInserter.fromHeader("X-API-Version"));
 		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
 	}
 
 	@Test
 	void queryParam() {
-		performRequest(DefaultApiVersionInserter.fromQueryParam("api-version"));
+		performRequest(ApiVersionInserter.fromQueryParam("api-version"));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path?api-version=1.2"));
 	}
 
 	@Test
 	void pathSegmentIndexLessThanSize() {
-		performRequest(DefaultApiVersionInserter.fromPathSegment(0).withVersionFormatter(v -> "v" + v));
+		performRequest(ApiVersionInserter.fromPathSegment(0).withVersionFormatter(v -> "v" + v));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/v1.2/path"));
 	}
 
 	@Test
 	void pathSegmentIndexEqualToSize() {
-		performRequest(DefaultApiVersionInserter.fromPathSegment(1).withVersionFormatter(v -> "v" + v));
+		performRequest(ApiVersionInserter.fromPathSegment(1).withVersionFormatter(v -> "v" + v));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path/v1.2"));
 	}
 
 	@Test
 	void pathSegmentIndexGreaterThanSize() {
 		assertThatIllegalStateException()
-				.isThrownBy(() -> performRequest(DefaultApiVersionInserter.fromPathSegment(2)))
+				.isThrownBy(() -> performRequest(ApiVersionInserter.fromPathSegment(2)))
 				.withMessage("Cannot insert version into '/path' at path segment index 2");
 	}
 
 	@Test
 	void defaultVersion() {
-		ApiVersionInserter inserter = DefaultApiVersionInserter.fromHeader("X-API-Version").build();
+		ApiVersionInserter inserter = ApiVersionInserter.fromHeader("X-API-Version").build();
 		RestClient restClient = restClientBuilder.defaultApiVersion(1.2).apiVersionInserter(inserter).build();
 		restClient.get().uri("/path").retrieve().body(String.class);
 
 		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
 	}
 
-	private void performRequest(DefaultApiVersionInserter.Builder builder) {
+	private void performRequest(ApiVersionInserter.Builder builder) {
 		ApiVersionInserter versionInserter = builder.build();
 		RestClient restClient = restClientBuilder.apiVersionInserter(versionInserter).build();
 

spring-web/src/test/java/org/springframework/web/client/support/RestClientAdapterTests.java

@@ -49,7 +49,7 @@ import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RequestPart;
-import org.springframework.web.client.DefaultApiVersionInserter;
+import org.springframework.web.client.ApiVersionInserter;
 import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.multipart.MultipartFile;
@@ -274,7 +274,7 @@ class RestClientAdapterTests {
 	void apiVersion() throws Exception {
 		RestClient restClient = RestClient.builder()
 				.baseUrl(anotherServer.url("/").toString())
-				.apiVersionInserter(DefaultApiVersionInserter.fromHeader("X-API-Version").build())
+				.apiVersionInserter(ApiVersionInserter.fromHeader("X-API-Version").build())
 				.build();
 
 		RestClientAdapter adapter = RestClientAdapter.create(restClient);

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientVersionTests.java

@@ -27,7 +27,6 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.web.client.ApiVersionInserter;
-import org.springframework.web.client.DefaultApiVersionInserter;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
@@ -59,45 +58,45 @@ public class WebClientVersionTests {
 
 	@Test
 	void header() {
-		performRequest(DefaultApiVersionInserter.fromHeader("X-API-Version"));
+		performRequest(ApiVersionInserter.fromHeader("X-API-Version"));
 		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
 	}
 
 	@Test
 	void queryParam() {
-		performRequest(DefaultApiVersionInserter.fromQueryParam("api-version"));
+		performRequest(ApiVersionInserter.fromQueryParam("api-version"));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path?api-version=1.2"));
 	}
 
 	@Test
 	void pathSegmentIndexLessThanSize() {
-		performRequest(DefaultApiVersionInserter.fromPathSegment(0).withVersionFormatter(v -> "v" + v));
+		performRequest(ApiVersionInserter.fromPathSegment(0).withVersionFormatter(v -> "v" + v));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/v1.2/path"));
 	}
 
 	@Test
 	void pathSegmentIndexEqualToSize() {
-		performRequest(DefaultApiVersionInserter.fromPathSegment(1).withVersionFormatter(v -> "v" + v));
+		performRequest(ApiVersionInserter.fromPathSegment(1).withVersionFormatter(v -> "v" + v));
 		expectRequest(request -> assertThat(request.getPath()).isEqualTo("/path/v1.2"));
 	}
 
 	@Test
 	void pathSegmentIndexGreaterThanSize() {
 		assertThatIllegalStateException()
-				.isThrownBy(() -> performRequest(DefaultApiVersionInserter.fromPathSegment(2)))
+				.isThrownBy(() -> performRequest(ApiVersionInserter.fromPathSegment(2)))
 				.withMessage("Cannot insert version into '/path' at path segment index 2");
 	}
 
 	@Test
 	void defaultVersion() {
-		ApiVersionInserter inserter = DefaultApiVersionInserter.fromHeader("X-API-Version").build();
+		ApiVersionInserter inserter = ApiVersionInserter.fromHeader("X-API-Version").build();
 		WebClient webClient = webClientBuilder.defaultApiVersion(1.2).apiVersionInserter(inserter).build();
 		webClient.get().uri("/path").retrieve().bodyToMono(String.class).block();
 
 		expectRequest(request -> assertThat(request.getHeader("X-API-Version")).isEqualTo("1.2"));
 	}
 
-	private void performRequest(DefaultApiVersionInserter.Builder builder) {
+	private void performRequest(ApiVersionInserter.Builder builder) {
 		ApiVersionInserter versionInserter = builder.build();
 		WebClient webClient = webClientBuilder.apiVersionInserter(versionInserter).build();
 		webClient.get().uri("/path").apiVersion(1.2).retrieve().bodyToMono(String.class).block();