Rearrange HttpHeaders adapters

This commit moves HttpHeaders that are used in multiple places (client
and server, reactive and non-reactive) to a new, separate http.support
package.

Closes gh-30823

spring-web/src/main/java/org/springframework/http/client/HttpComponentsClientHttpResponse.java

@@ -20,13 +20,14 @@
 import java.io.InputStream;
 
 import org.apache.hc.core5.http.ClassicHttpResponse;
-import org.apache.hc.core5.http.Header;
 import org.apache.hc.core5.http.HttpEntity;
 import org.apache.hc.core5.http.io.entity.EntityUtils;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
+import org.springframework.http.support.HttpComponentsHeadersAdapter;
 import org.springframework.lang.Nullable;
+import org.springframework.util.MultiValueMap;
 
 /**
  * {@link ClientHttpResponse} implementation based on
@@ -65,10 +66,8 @@ public String getStatusText() {
 	@Override
 	public HttpHeaders getHeaders() {
 		if (this.headers == null) {
-			this.headers = new HttpHeaders();
-			for (Header header : this.httpResponse.getHeaders()) {
-				this.headers.add(header.getName(), header.getValue());
-			}
+			MultiValueMap<String, String> adapter = new HttpComponentsHeadersAdapter(this.httpResponse);
+			this.headers = HttpHeaders.readOnlyHttpHeaders(adapter);
 		}
 		return this.headers;
 	}

spring-web/src/main/java/org/springframework/http/client/JettyClientHttpResponse.java

@@ -23,10 +23,11 @@
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
+import org.springframework.http.support.JettyHeadersAdapter;
 import org.springframework.util.MultiValueMap;
 
 /**
- * {@link ClientHttpResponse} implementation based on based on Jetty's
+ * {@link ClientHttpResponse} implementation based on Jetty's
  * {@link org.eclipse.jetty.client.HttpClient}.
  *
  * @author Arjen Poutsma

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsClientHttpRequest.java

@@ -40,6 +40,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
+import org.springframework.http.support.HttpComponentsHeadersAdapter;
 import org.springframework.lang.Nullable;
 
 /**

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsClientHttpResponse.java

@@ -31,6 +31,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.ResponseCookie;
+import org.springframework.http.support.HttpComponentsHeadersAdapter;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 

spring-web/src/main/java/org/springframework/http/client/reactive/JettyClientHttpRequest.java

@@ -37,7 +37,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
-import org.springframework.http.client.JettyHeadersAdapter;
+import org.springframework.http.support.JettyHeadersAdapter;
 
 /**
  * {@link ClientHttpRequest} implementation for the Jetty ReactiveStreams HTTP client.

spring-web/src/main/java/org/springframework/http/client/reactive/JettyClientHttpResponse.java

@@ -29,7 +29,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.ResponseCookie;
-import org.springframework.http.client.JettyHeadersAdapter;
+import org.springframework.http.support.JettyHeadersAdapter;
 import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;

spring-web/src/main/java/org/springframework/http/client/reactive/ReactorClientHttpRequest.java

@@ -33,6 +33,7 @@
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.ZeroCopyHttpOutputMessage;
+import org.springframework.http.support.Netty4HeadersAdapter;
 
 /**
  * {@link ClientHttpRequest} implementation for the Reactor-Netty HTTP client.
@@ -136,7 +137,7 @@ protected void applyCookies() {
 
 	@Override
 	protected HttpHeaders initReadOnlyHeaders() {
-		return HttpHeaders.readOnlyHttpHeaders(new NettyHeadersAdapter(this.request.requestHeaders()));
+		return HttpHeaders.readOnlyHttpHeaders(new Netty4HeadersAdapter(this.request.requestHeaders()));
 	}
 
 }