fix: Split out server related code from a2a-java-sdk-core into a new a2a-java-sdk-server-common module (#129)

This PR splits out server related code from the `a2a-java-sdk-core`
module into a new `a2a-java-sdk-server-common` module that is used by
the quarkus and jakarta server modules.

This reduces the dependencies required by the `a2a-java-sdk-core`
module.

Author: fjuma

README.md

@@ -50,10 +50,10 @@ The A2A Java SDK provides a Java server implementation of the [Agent2Agent (A2A)
 ### 2. Add a class that creates an A2A Agent Card
 
 ```java
+import io.a2a.server.PublicAgentCard;
 import io.a2a.spec.AgentCapabilities;
 import io.a2a.spec.AgentCard;
 import io.a2a.spec.AgentSkill;
-import io.a2a.spec.PublicAgentCard;
 ...
 
 @ApplicationScoped

core/pom.xml

@@ -25,24 +25,6 @@
             <groupId>com.fasterxml.jackson.datatype</groupId>
             <artifactId>jackson-datatype-jsr310</artifactId>
         </dependency>
-        <dependency>
-            <groupId>io.smallrye.reactive</groupId>
-            <artifactId>mutiny-zero</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>jakarta.enterprise</groupId>
-            <artifactId>jakarta.enterprise.cdi-api</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>io.quarkus</groupId>
-            <artifactId>quarkus-arc</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>

core/src/main/java/io/a2a/client/A2ACardResolver.java

@@ -4,15 +4,11 @@
 
 import java.io.IOException;
 import java.util.Map;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.atomic.AtomicReference;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import io.a2a.http.A2AHttpClient;
 import io.a2a.http.A2AHttpResponse;
-import io.a2a.spec.A2A;
 import io.a2a.spec.A2AClientError;
 import io.a2a.spec.A2AClientJSONError;
 import io.a2a.spec.AgentCard;

core/src/main/java/io/a2a/client/sse/SSEEventListener.java

@@ -4,17 +4,16 @@
 
 import java.util.concurrent.Future;
 import java.util.function.Consumer;
+import java.util.logging.Logger;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import io.a2a.spec.JSONRPCError;
 import io.a2a.spec.StreamingEventKind;
 import io.a2a.spec.TaskStatusUpdateEvent;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 public class SSEEventListener {
-    private static final Logger log = LoggerFactory.getLogger(SSEEventListener.class);
+    private static final Logger log = Logger.getLogger(SSEEventListener.class.getName());
     private final Consumer<StreamingEventKind> eventHandler;
     private final Consumer<JSONRPCError> errorHandler;
     private final Runnable failureHandler;
@@ -29,7 +28,7 @@ public void onMessage(String message, Future<Void> completableFuture) {
         try {
             handleMessage(OBJECT_MAPPER.readTree(message),completableFuture);
         } catch (JsonProcessingException e) {
-            log.warn("Failed to parse JSON message: {}", message, e);
+            log.warning("Failed to parse JSON message: " + message);
         }
     }
 

core/src/main/java/io/a2a/http/JdkA2AHttpClient.java

@@ -14,9 +14,6 @@
 import java.util.concurrent.Flow;
 import java.util.function.Consumer;
 
-import jakarta.enterprise.context.ApplicationScoped;
-
-@ApplicationScoped
 public class JdkA2AHttpClient implements A2AHttpClient {
 
     private final HttpClient httpClient;

core/src/main/java/io/a2a/server/events/Event.java

@@ -1,6 +1,4 @@
 package io.a2a.spec;
 
-import io.a2a.server.events.Event;
-
 public interface A2AError extends Event {
 }

core/src/main/java/io/a2a/spec/A2AError.java

@@ -0,0 +1,4 @@
+package io.a2a.spec;
+
+public interface Event {
+}

core/src/main/java/io/a2a/spec/Event.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 
-import io.a2a.server.events.Event;
 import io.a2a.util.Assert;
 
 /**

core/src/main/java/io/a2a/spec/JSONRPCError.java

@@ -7,7 +7,6 @@
 
 import com.fasterxml.jackson.annotation.JsonSubTypes;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
-import io.a2a.server.events.Event;
 
 @JsonTypeInfo(
         use = JsonTypeInfo.Id.NAME,