Inject Pooling Connection Manager

src/main/java/com/adyen/httpclient/AdyenHttpClient.java

@@ -56,7 +56,9 @@
 import org.apache.hc.client5.http.config.ConnectionConfig;
 import org.apache.hc.client5.http.config.RequestConfig;
 import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
 import org.apache.hc.client5.http.impl.classic.HttpClients;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
 import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
 import org.apache.hc.client5.http.ssl.SSLConnectionSocketFactory;
 import org.apache.hc.core5.http.HttpHost;
@@ -91,9 +93,33 @@ public class AdyenHttpClient implements ClientInterface {
 
   private static final String CHARSET = "UTF-8";
   private Proxy proxy;
+  private final PoolingHttpClientConnectionManager sharedConnectionManager;
   private volatile CloseableHttpClient sharedHttpClient;
   private final Object lock = new Object();
 
+  public AdyenHttpClient() {
+    this(null);
+  }
+
+  /**
+   * Creates an AdyenHttpClient with a shared connection manager.
+   * <p>
+   * <b>Note:</b> When using a shared connection manager:
+   * <ul>
+   *   <li>Any custom {@link SSLContext} or {@link HostnameVerifier} configured in {@link Config}
+   *       will be ignored, as the connection manager's own socket factory registry is used.</li>
+   *   <li>Connection-level configurations (such as {@code connectTimeout} and {@code socketTimeout})
+   *       must be pre-configured on the shared connection manager, as the timeouts from {@link Config}
+   *       will only be applied at the request level (via {@link RequestConfig}).</li>
+   * </ul>
+   * </p>
+   * 
+   * @param connectionManager the shared connection manager to use
+   */
+  public AdyenHttpClient(PoolingHttpClientConnectionManager connectionManager) {
+    this.sharedConnectionManager = connectionManager;
+  }
+
   /**
    * Returns the proxy configured for this HTTP client.
    *
@@ -372,7 +398,12 @@ private CloseableHttpClient createHttpClientWithSocketFactory(
                 config.getConnectionRequestTimeoutMillis(), TimeUnit.MILLISECONDS)
             .setDefaultKeepAlive(config.getDefaultKeepAliveMillis(), TimeUnit.MILLISECONDS)
             .build();
-    ConnectionConfig connectionConfig =
+
+    HttpClientBuilder clientBuilder = HttpClients.custom();
+    if (sharedConnectionManager != null) {
+      clientBuilder = clientBuilder.setConnectionManager(sharedConnectionManager).setConnectionManagerShared(true);
+    } else {
+      ConnectionConfig connectionConfig =
         ConnectionConfig.custom()
             .setConnectTimeout(config.getConnectionTimeoutMillis(), TimeUnit.MILLISECONDS)
             // socketTimeout acts as an OS-level safety net for stalled reads;
@@ -381,12 +412,14 @@ private CloseableHttpClient createHttpClientWithSocketFactory(
             // fires first.
             .setSocketTimeout(config.getReadTimeoutMillis(), TimeUnit.MILLISECONDS)
             .build();
-    return HttpClients.custom()
-        .setConnectionManager(
+      clientBuilder = clientBuilder.setConnectionManager(
             PoolingHttpClientConnectionManagerBuilder.create()
                 .setSSLSocketFactory(socketFactory)
                 .setDefaultConnectionConfig(connectionConfig)
-                .build())
+                .build());
+    }
+
+    return clientBuilder
         .setDefaultRequestConfig(defaultRequestConfig)
         .setRedirectStrategy(new AdyenCustomRedirectStrategy())
         .build();