public void remove(final K key) {
        multiChange((putAction, removeAction) -> removeAction.call(key));
    }
Performs a multi-change
<br>
The given action is supposed to execute the action. It gets passed two action parameter:
* the first one takes a key-value-pair and will PUT this pair to the map when called
* the second one takes a key and will REMOVE this key from the map when called
main/src/main/java/cgeo/geocaching/utils/AsynchronousMapWrapper.java