715             }
 716 
 717             // ise thrown from function is not a cme.
 718             v = function.apply(k, v);
 719 
 720             try {
 721                 entry.setValue(v);
 722             } catch (IllegalStateException ise) {
 723                 // this usually means the entry is no longer in the map.
 724                 throw new ConcurrentModificationException(ise);
 725             }
 726         }
 727     }
 728 
 729     /**
 730      * If the specified key is not already associated with a value (or is mapped
 731      * to {@code null}) associates it with the given value and returns
 732      * {@code null}, else returns the current value.
 733      *
 734      * @implSpec
 735      * The default implementation is equivalent to, for this {@code
 736      * map}:
 737      *
 738      * <pre> {@code
 739      * V v = map.get(key);
 740      * if (v == null)
 741      *     v = map.put(key, value);
 742      *
 743      * return v;
 744      * }</pre>
 745      *
 746      * <p>The default implementation makes no guarantees about synchronization
 747      * or atomicity properties of this method. Any implementation providing
 748      * atomicity guarantees must override this method and document its
 749      * concurrency properties.
 750      *
 751      * @param key key with which the specified value is to be associated
 752      * @param value value to be associated with the specified key
 753      * @return the previous value associated with the specified key, or
 754      *         {@code null} if there was no mapping for the key.
 755      *         (A {@code null} return can also indicate that the map
 756      *         previously associated {@code null} with the key,

 715             }
 716 
 717             // ise thrown from function is not a cme.
 718             v = function.apply(k, v);
 719 
 720             try {
 721                 entry.setValue(v);
 722             } catch (IllegalStateException ise) {
 723                 // this usually means the entry is no longer in the map.
 724                 throw new ConcurrentModificationException(ise);
 725             }
 726         }
 727     }
 728 
 729     /**
 730      * If the specified key is not already associated with a value (or is mapped
 731      * to {@code null}) associates it with the given value and returns
 732      * {@code null}, else returns the current value.
 733      *
 734      * @implSpec
 735      * The default implementation is equivalent to, for this {@code map}:

 736      *
 737      * <pre> {@code
 738      * V v = map.get(key);
 739      * if (v == null)
 740      *     v = map.put(key, value);
 741      *
 742      * return v;
 743      * }</pre>
 744      *
 745      * <p>The default implementation makes no guarantees about synchronization
 746      * or atomicity properties of this method. Any implementation providing
 747      * atomicity guarantees must override this method and document its
 748      * concurrency properties.
 749      *
 750      * @param key key with which the specified value is to be associated
 751      * @param value value to be associated with the specified key
 752      * @return the previous value associated with the specified key, or
 753      *         {@code null} if there was no mapping for the key.
 754      *         (A {@code null} return can also indicate that the map
 755      *         previously associated {@code null} with the key,