Removes all of the mappings from this map (optional operation).

  Removes all of the mappings from this map (optional operation).
The map will be empty after this call returns.

  Returns true if this map contains a mapping for the specified key.

  Returns true if this map contains a mapping for the specified
key. More formally, returns true if and only if
this map contains a mapping for a key k such that
(key==null ? k==null : key.equals(k)). (There can be
at most one such mapping.)
Returns: true if this map contains a mapping for the specified key.
Parameters:
- key - key whose presence in this map is to be tested.
Throws:
- NullPointerException - if key is null
- ClassCastException - if key is not String
- IllegalArgumentException - if key is empty String

  Returns true if this map maps one or more keys to the specified value.

  Returns true if this map maps one or more keys to the
specified value. More formally, returns true if and only if
this map contains at least one mapping to a value v such that
(value==null ? v==null : value.equals(v)). This operation
will probably require time linear in the map size for most
implementations of the Map interface.

  Returns a Set view of the mappings contained in this map.

  Returns a Set view of the mappings contained in this map.
The set is backed by the map, so changes to the map are
reflected in the set, and vice-versa. If the map is modified
while an iteration over the set is in progress (except through
the iterator's own remove operation, or through the
setValue operation on a map entry returned by the
iterator) the results of the iteration are undefined. The set
supports element removal, which removes the corresponding
mapping from the map, via the Iterator.remove,
Set.remove, removeAll, retainAll and
clear operations. It does not support the
add or addAll operations.

  Returns the value to which this map maps the specified key.

  Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

More formally, if this map contains a mapping from a key k to a value v such that (key==null ? k==null : key.equals(k)), then this method returns v; otherwise it returns null. (There can be at most one such mapping.)
Returns: the value to which this map maps the specified key, or null if the map contains no mapping for this key.
Parameters:
- key - key whose associated value is to be returned.
Throws:
- NullPointerException - if key is null
- ClassCastException - if key is not String
- IllegalArgumentException - if key is empty String

Returns true if this map contains no key-value mappings.

  Returns a Set view of the keys contained in this map.

  Returns a Set view of the keys contained in this map.
The set is backed by the map, so changes to the map are
reflected in the set, and vice-versa. If the map is modified
while an iteration over the set is in progress (except through
the iterator's own remove operation), the results of
the iteration are undefined. The set supports element removal,
which removes the corresponding mapping from the map, via the
Iterator.remove, Set.remove,
removeAll, retainAll, and clear
operations. It does not support the add or addAll
operations.

  Sets the specified key/value in the underlying map field.

  Sets the specified key/value in the underlying map field.
Returns: Previous value for the specified key. Returns null if key was previously unset.
Parameters:
- name - Name of value
- value - Value to set.
Throws:
- NullPointerException - if the name is null.
- IllegalArgumentException - if the name is empty.

  putAll is implemented using Map.putAll.

  putAll is implemented using Map.putAll.
Parameters:
- toMerge - The Map of values to add.
Throws:
- NullPointerException - if toMerge map is null or if some key in the map is null.
- IllegalArgumentException - if some key in the map is an empty String.

  Removes the mapping for this key from this map if it is present (optional operation).

  Removes the mapping for this key from this map if it is present (optional operation). More formally, if this map contains a mapping from key k to value v such that (key==null ? k==null : key.equals(k)), that mapping is removed. (The map can contain at most one such mapping.)

Returns the value to which the map previously associated the key, or null if the map contained no mapping for this key. (A null return can also indicate that the map previously associated null with the specified key if the implementation supports null values.) The map will not contain a mapping for the specified key once the call returns.
Returns: previous value associated with specified key, or null if there was no mapping for key.
Parameters:
- key - key whose mapping is to be removed from the map.
Throws:
- NullPointerException - if key is null
- ClassCastException - if key is not String
- IllegalArgumentException - if key is empty String

  Returns the number of key-value mappings in this map.

  Returns the number of key-value mappings in this map. If the
map contains more than Integer.MAX_VALUE elements, returns
Integer.MAX_VALUE.

  Returns a Collection view of the values contained in this map.

  Returns a Collection view of the values contained in this map.
The collection is backed by the map, so changes to the map are
reflected in the collection, and vice-versa. If the map is
modified while an iteration over the collection is in progress
(except through the iterator's own remove operation),
the results of the iteration are undefined. The collection
supports element removal, which removes the corresponding
mapping from the map, via the Iterator.remove,
Collection.remove, removeAll,
retainAll and clear operations. It does not
support the add or addAll operations.