feat: implement partial event aggregation in RemoteA2AAgent

PiperOrigin-RevId: 877812730

Author: google-genai-bot

a2a/pom.xml

@@ -52,6 +52,11 @@
       <artifactId>jackson-databind</artifactId>
       <version>${jackson.version}</version>
     </dependency>
+    <dependency>
+      <groupId>com.fasterxml.jackson.datatype</groupId>
+      <artifactId>jackson-datatype-jsr310</artifactId>
+      <version>${jackson.version}</version>
+    </dependency>
     <dependency>
       <groupId>com.fasterxml.jackson.module</groupId>
       <artifactId>jackson-module-parameter-names</artifactId>