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: {@code true} if the specified object is equal to this map entry
Parameters:
- o - object to be compared for equality with this map entry
See Also: AbstractMap.SimpleImmutableEntry.hashCode(),

  Returns the key corresponding to this entry.

  Returns the key corresponding to this entry.
Returns: the key corresponding to this entry

  Returns the value corresponding to this entry.

  Returns the value corresponding to this entry.
Returns: the value corresponding to this entry

  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: AbstractMap.SimpleImmutableEntry.equals(java.lang.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). This implementation simply throws
UnsupportedOperationException, as this class implements
an immutable map entry.
Returns: (Does not return)
Parameters:
- value - new value to be stored in this entry
Throws:
- UnsupportedOperationException - always

  Returns a String representation of this map entry.

  Returns a String representation of this map entry. This
implementation returns the string representation of this
entry's key followed by the equals character ("=")
followed by the string representation of this entry's value.
Returns: a String representation of this map entry