https://github.com/spring-projects/spring-framework: Spring Web (Spring IO)
  • Juergen Hoeller 
This package provides generic HTTP support classes,
to be used by higher-level classes like RestTemplate.

/**
 * This package provides generic HTTP support classes,
 * to be used by higher-level classes like RestTemplate.
 */
@NonNullApi
@NonNullFields
package org.springframework.http.client.support;

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