http://findbugs.sourceforge.net/: JSR305 Annotations for Findbugs 
/*
 * Copyright (c) 2005 Brian Goetz
 * Released under the Creative Commons Attribution License
 *   (http://creativecommons.org/licenses/by/2.5)
 * Official home: http://www.jcip.net
 */
package javax.annotation.concurrent;

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


The class to which this annotation is applied is thread-safe. This means that
no sequences of accesses (reads and writes to public fields, calls to public
methods) may put the object into an invalid state, regardless of the
interleaving of those actions by the runtime, and without requiring any
additional synchronization or coordination on the part of the caller.

See Also:
  • NotThreadSafe
/**
 * The class to which this annotation is applied is thread-safe. This means that
 * no sequences of accesses (reads and writes to public fields, calls to public
 * methods) may put the object into an invalid state, regardless of the
 * interleaving of those actions by the runtime, and without requiring any
 * additional synchronization or coordination on the part of the caller.
 *
 * @see NotThreadSafe
 */
@Documented
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.CLASS)
public @interface ThreadSafe {
}