@return a new transformed map
@param map the map to decorate, must not be null
file : https_github_com_apache_commons-collections_git/src/main/java/org/apache/commons/collections4/splitmap/TransformedSplitMap.java
file : https_github_com_apache_commons-collections_git/src/main/java/org/apache/commons/collections4/map/TransformedMap.java