public static boolean unregisterExtension(String key) {
        if (key == null) {
            throw new IllegalArgumentException(
                            "Parameter 'key' can not be null");
        }
        w.lock();
        try {
            return extensionMap.remove(key) != null;
        } finally {
            w.unlock();
        }
    }
public static boolean unregisterExtension ( String key ) { if ( key == null ) { throw new IllegalArgumentException ( "Parameter 'key' can not be null" ) ; } w . lock ( ) ; try { return extensionMap . remove ( key ) != null ; } finally { w . unlock ( ) ; } }
Removes context extension registration.

@param key
String key associated with the registered extension.
@return <code>true</code> if key had extension associated with it.
@throws IllegalArgumentException
if parameter <code>key</code> is <code>null</code>.