resent-1.8/src/main/java/javax/annotation/Nonnull.java

package javax.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import javax.annotation.meta.TypeQualifier;
import javax.annotation.meta.TypeQualifierValidator;
import javax.annotation.meta.When;

/**
 * The annotated element must not be null.
 * <p>
 * Annotated fields must not be null after construction has completed.
 * <p>
 * When this annotation is applied to a method it applies to the method return
 * value.
 */
@Documented
@TypeQualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface Nonnull {
    When when() default When.ALWAYS;

    class Checker implements TypeQualifierValidator<Nonnull> {

        public When forConstantValue(Nonnull qualifierArgument, Object value) {
            if (value == null) return When.NEVER;
            return When.ALWAYS;
        }
    }
}