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.locks.Lock.

The argument determines which lock guards the annotated field or method:

• this : The string literal "this" means that this field is guarded by the class in which it 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.