https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
Support classes for application events, like standard context events.
To be supported by all major application context implementations.

/**
 * Support classes for application events, like standard context events.
 * To be supported by all major application context implementations.
 */
@NonNullApi
@NonNullFields
package org.springframework.context.event;

import org.springframework.lang.NonNullApi;
import org.springframework.lang.NonNullFields;