A2A Java SDK: Push notification credentials logged in cleartext on protobuf parse failure

A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Prior to 1.3.0.Final, RestHandler.parseRequestBody in `transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java` logs the entire JSON request body at SEVERE level when JsonFormat.parser().merge() throws InvalidProtocolBufferException. With push notifications enabled, createTaskPushNotificationConfiguration reaches this parser for requests to `/v1/tenants/{tenant}/tasks/{taskId}/pushNotificationConfigs`, whose token and authentication.credentials fields can contain bearer tokens and authentication credentials for client push endpoints. A valid JSON body that fails protobuf deserialization, including an unknown field under strict parsing or a schema mismatch, causes those secrets to be written to the server logs in cleartext. An attacker with access to the server logs or a log aggregation system can retrieve the credentials and potentially use the credentials to send forged task status updates to the client's push notification endpoint. This issue is fixed in version 1.3.0.Final.