Adding the client side integration of otel

Signed-off-by: Emmanuel Hugonnet <[email protected]>

Author: ehsavoie

client/base/src/main/java/io/a2a/client/ClientBuilder.java

@@ -9,6 +9,7 @@
 import io.a2a.spec.AgentCard;
 import io.a2a.spec.AgentInterface;
 import io.a2a.spec.TransportProtocol;
+import java.lang.reflect.InvocationTargetException;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -37,7 +38,8 @@ public class ClientBuilder {
     private final AgentCard agentCard;
 
     private final List<BiConsumer<ClientEvent, AgentCard>> consumers = new ArrayList<>();
-    private @Nullable Consumer<Throwable> streamErrorHandler;
+    private @Nullable
+    Consumer<Throwable> streamErrorHandler;
     private ClientConfig clientConfig = new ClientConfig.Builder().build();
 
     private final Map<Class<? extends ClientTransport>, ClientTransportConfig<? extends ClientTransport>> clientTransports = new LinkedHashMap<>();
@@ -105,7 +107,7 @@ private ClientTransport buildClientTransport() throws A2AClientException {
             throw new A2AClientException("Missing required TransportConfig for " + agentInterface.transport());
         }
 
-        return clientTransportProvider.create(clientTransportConfig, agentCard, agentInterface.url());
+        return wrap(clientTransportProvider.create(clientTransportConfig, agentCard, agentInterface.url()), clientTransportConfig);
     }
 
     private Map<String, String> getServerPreferredTransports() {
@@ -160,10 +162,21 @@ private AgentInterface findBestClientTransport() throws A2AClientException {
         if (transportProtocol == null || transportUrl == null) {
             throw new A2AClientException("No compatible transport found");
         }
-        if (! transportProviderRegistry.containsKey(transportProtocol)) {
+        if (!transportProviderRegistry.containsKey(transportProtocol)) {
             throw new A2AClientException("No client available for " + transportProtocol);
         }
 
         return new AgentInterface(transportProtocol, transportUrl);
     }
+
+    private ClientTransport wrap(ClientTransport transport, ClientTransportConfig<? extends ClientTransport> clientTransportConfig) {
+        try {
+            Class<?> factoryClass = this.getClass().getClassLoader().loadClass("io.a2a.extras.opentelemetry.OpenTelemetryClientTransportFactory");
+            Object openTelemetryClientTransportFactory = factoryClass.getConstructor(new Class<?>[0]).newInstance(new Object[0]);
+            factoryClass.getDeclaredMethod("config", ClientTransportConfig.class).invoke(openTelemetryClientTransportFactory, clientTransportConfig);
+            return (ClientTransport) factoryClass.getDeclaredMethod("wrap", ClientTransport.class).invoke(openTelemetryClientTransportFactory, transport);
+        } catch (ClassNotFoundException | NoSuchMethodException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException ex) {
+            return transport;
+        }
+    }
 }

client/transport/rest/src/main/java/io/a2a/client/transport/rest/RestTransportConfig.java

@@ -4,7 +4,7 @@
 import io.a2a.client.transport.spi.ClientTransportConfig;
 import org.jspecify.annotations.Nullable;
 
-public class RestTransportConfig extends ClientTransportConfig<RestTransport>  {
+public class RestTransportConfig extends ClientTransportConfig<RestTransport> {
 
     private final @Nullable A2AHttpClient httpClient;
 

client/transport/spi/src/main/java/io/a2a/client/transport/spi/ClientTransportConfig.java

@@ -2,15 +2,18 @@
 
 import io.a2a.client.transport.spi.interceptors.ClientCallInterceptor;
 import java.util.ArrayList;
+import java.util.HashMap;
 
 import java.util.List;
+import java.util.Map;
 
 /**
  * Configuration for an A2A client transport.
  */
 public abstract class ClientTransportConfig<T extends ClientTransport> {
 
     protected List<ClientCallInterceptor> interceptors = new ArrayList<>();
+    protected Map<String, ? extends Object > parameters = new HashMap<>();
 
     public void setInterceptors(List<ClientCallInterceptor> interceptors) {
         this.interceptors = new ArrayList<>(interceptors);
@@ -19,4 +22,12 @@ public void setInterceptors(List<ClientCallInterceptor> interceptors) {
     public List<ClientCallInterceptor> getInterceptors() {
         return interceptors;
     }
+
+    public void setParameters(Map<String, ? extends Object > parameters) {
+        this.parameters = new HashMap<>(parameters);
+    }
+
+    public Map<String, ? extends Object > getParameters() {
+        return parameters;
+    }
 }