http://findbugs.sourceforge.net/: Annotation the FindBugs tool supports 
/*
 * Copyright (c) 2005 Brian Goetz and Tim Peierls
 * Released under the Creative Commons Attribution License
 *   (http://creativecommons.org/licenses/by/2.5)
 * Official home: http://www.jcip.net
 *
 * Any republication or derived work distributed in source code form
 * must include this copyright and license notice.
 */

package net.jcip.annotations;

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


The field or method to which this annotation is applied can only be accessed
when holding a particular lock, which may be a built-in (synchronization) lock,
or may be an explicit java.util.concurrent.Lock.
The argument determines which lock guards the annotated field or method:

    

  • 
this : The intrinsic lock of the object in whose class the field is defined.

    • 

  • 
class-name.this : For inner classes, it may be necessary to disambiguate 'this';
the class-name.this designation allows you to specify which 'this' reference is intended

    • 

  • 
itself : For reference fields only; the object to which the field refers.

    • 

  • 
field-name : The lock object is referenced by the (instance or static) field
specified by field-name.

    • 

  • 
class-name.field-name : The lock object is reference by the static field specified
by class-name.field-name.

    • 

  • 
method-name() : The lock object is returned by calling the named nil-ary method.

    • 

  • 
class-name.class : The Class object for the specified class should be used as the lock object.

    • 

/**
 * The field or method to which this annotation is applied can only be accessed
 * when holding a particular lock, which may be a built-in (synchronization) lock,
 * or may be an explicit java.util.concurrent.Lock.
 *
 * The argument determines which lock guards the annotated field or method:
 * <ul>
 * <li>
 * <code>this</code> : The intrinsic lock of the object in whose class the field is defined.
 * </li>
 * <li>
 * <code>class-name.this</code> : For inner classes, it may be necessary to disambiguate 'this';
 * the <em>class-name.this</em> designation allows you to specify which 'this' reference is intended
 * </li>
 * <li>
 * <code>itself</code> : For reference fields only; the object to which the field refers.
 * </li>
 * <li>
 * <code>field-name</code> : The lock object is referenced by the (instance or static) field
 * specified by <em>field-name</em>.
 * </li>
 * <li>
 * <code>class-name.field-name</code> : The lock object is reference by the static field specified
 * by <em>class-name.field-name</em>.
 * </li>
 * <li>
 * <code>method-name()</code> : The lock object is returned by calling the named nil-ary method.
 * </li>
 * <li>
 * <code>class-name.class</code> : The Class object for the specified class should be used as the lock object.
 * </li>
 */
@Target({ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface GuardedBy {
    String value();
}