http://findbugs.sourceforge.net/: JSR305 Annotations for Findbugs 
package javax.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

import javax.annotation.meta.TypeQualifierNickname;
import javax.annotation.meta.When;


Used to annotate a value that may be either negative or nonnegative, and
indicates that uses of it should check for
negative values before using it in a way that requires the value to be
nonnegative, and check for it being nonnegative before using it in a way that
requires it to be negative.

/**
 * Used to annotate a value that may be either negative or nonnegative, and
 * indicates that uses of it should check for
 * negative values before using it in a way that requires the value to be
 * nonnegative, and check for it being nonnegative before using it in a way that
 * requires it to be negative.
 */
@Documented
@TypeQualifierNickname
@Nonnegative(when = When.MAYBE)
@Retention(RetentionPolicy.RUNTIME)
public @interface CheckForSigned {

}