Deprecate Apache 4.x HTTP Client

ApacheHttpClient, which is based on Apache HttpClient 4.x is being
deprecated in favor of the Apache 5.x HTTP client.

The Apache 5.x client has already replaced the 4.x client as the default sync
HTTP client since 2.46.0.

Apache 5.x is actively maintained and receives new feature updates whereas
Apache 4.x is in maintenance mode, only receiving critical fixes.

Author: dagnir

http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ApacheHttpClient.java

@@ -101,8 +101,13 @@
  * <p>See software.amazon.awssdk.http.urlconnection.UrlConnectionHttpClient for an alternative implementation.</p>
  *
  * <p>This can be created via {@link #builder()}</p>
+ *
+ * @deprecated Apache 4.x is in maintenance mode. Users are encouraged to switch to the
+ * <a href="https://docs.aws.amazon.com/java/api/latest/software/amazon/awssdk/http/apache5/Apache5HttpClient.html">Apache 5 HTTP Client</a>
+ * which is feature compatible with this client.
  */
 @SdkPublicApi
+@Deprecated
 public final class ApacheHttpClient implements SdkHttpClient {
 
     public static final String CLIENT_NAME = "Apache";
@@ -345,6 +350,9 @@ public String clientName() {
      *                     .socketTimeout(Duration.ofSeconds(10))
      *                     .build();
      * </pre>
+     * @deprecated Apache 4.x is in maintenance mode. Users are encouraged to switch to the
+     * <a href="https://docs.aws.amazon.com/java/api/latest/software/amazon/awssdk/http/apache5/Apache5HttpClient.html">Apache 5 HTTP Client</a>
+     * which is feature compatible with this client.
      */
     public interface Builder extends SdkHttpClient.Builder<ApacheHttpClient.Builder> {
 

http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ApacheSdkHttpService.java

@@ -21,6 +21,10 @@
 
 /**
  * Service binding for the Apache implementation.
+ *
+ * @deprecated Apache 4.x is in maintenance mode. Users are encouraged to switch to the
+ * <a href="https://docs.aws.amazon.com/java/api/latest/software/amazon/awssdk/http/apache5/Apache5HttpClient.html">Apache 5 HTTP Client</a>
+ * which is feature compatible with this client.
  */
 @SdkPublicApi
 public class ApacheSdkHttpService implements SdkHttpService {

http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ProxyConfiguration.java

@@ -32,8 +32,13 @@
 
 /**
  * Configuration that defines how to communicate via an HTTP or HTTPS proxy.
+ *
+ * @deprecated Apache 4.x is in maintenance mode. Users are encouraged to switch to the
+ * <a href="https://docs.aws.amazon.com/java/api/latest/software/amazon/awssdk/http/apache5/Apache5HttpClient.html">Apache 5 HTTP Client</a>
+ * which is feature compatible with this client.
  */
 @SdkPublicApi
+@Deprecated
 public final class ProxyConfiguration implements ToCopyableBuilder<ProxyConfiguration.Builder, ProxyConfiguration> {
     private final URI endpoint;
     private final String username;