https://github.com/spring-projects/spring-framework: Spring Expression Language (SpEL) (Spring IO)
  • Juergen Hoeller 
SpEL's central implementation package.

/**
 * SpEL's central implementation package.
 */
@NonNullApi
@NonNullFields
package org.springframework.expression.spel;

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