Compares the specified object with this entry for equality.

  Compares the specified object with this entry for equality.
Returns true if the given object is also a map entry and
the two entries represent the same mapping. More formally, two
entries e1 and e2 represent the same mapping
if

     (e1.getKey()==null ?
      e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &&
     (e1.getValue()==null ?
      e2.getValue()==null : e1.getValue().equals(e2.getValue()))
 

This ensures that the equals method works properly across
different implementations of the Map.Entry interface.
Returns: true if the specified object is equal to this map entry
Parameters:
- o - object to be compared for equality with this map entry

  Returns the key corresponding to this entry.

  Returns the key corresponding to this entry.
Returns: the key corresponding to this entry
Throws:
- IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.

  Returns the value corresponding to this entry.

  Returns the value corresponding to this entry. If the mapping
has been removed from the backing map (by the iterator's
remove operation), the results of this call are undefined.
Returns: the value corresponding to this entry
Throws:
- IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.

  Returns the hash code value for this map entry.

  Returns the hash code value for this map entry. The hash code
of a map entry e is defined to be:

     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
     (e.getValue()==null ? 0 : e.getValue().hashCode())
 

This ensures that e1.equals(e2) implies that
e1.hashCode()==e2.hashCode() for any two Entries
e1 and e2, as required by the general
contract of Object.hashCode.
Returns: the hash code value for this map entry
See Also: Object.hashCode(), Object.equals(Object), Map.Entry.equals(Object),

  Replaces the value corresponding to this entry with the specified value (optional operation).

  Replaces the value corresponding to this entry with the specified
value (optional operation). (Writes through to the map.) The
behavior of this call is undefined if the mapping has already been
removed from the map (by the iterator's remove operation).
Returns: old value corresponding to the entry
Parameters:
- value - new value to be stored in this entry
Throws:
- UnsupportedOperationException - if the put operation is not supported by the backing map
- ClassCastException - if the class of the specified value prevents it from being stored in the backing map
- NullPointerException - if the backing map does not permit null values, and the specified value is null
- IllegalArgumentException - if some property of this value prevents it from being stored in the backing map
- IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map.