Amazon OpenSearch Notifications - java.lang.NoClassDefFoundError

I am facing an issue while testing notifications in Amazon OpenSearch. When attempting to test the notifications from the dashboard, I encounter a java.lang.NoClassDefFoundError with reference to javax.activation.DataSource. The error message indicates that the class is not found during runtime. As I am using a managed service from AWS, I do not have direct access to the underlying nodes to modify the classpath or install additional libraries. My AWS plan does not include technical support. Can someone from the AWS community help me troubleshoot this error and provide suggestions on how to resolve it in a managed Amazon OpenSearch environment? Any insights or guidance would be highly appreciated. Thank you!