https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
Contains classes defining the application context subinterface
for UI applications. The theme feature is added here.

/**
 * Contains classes defining the application context subinterface
 * for UI applications. The theme feature is added here.
 */
@NonNullApi
@NonNullFields
package org.springframework.ui.context;

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