@Override
    public boolean containsKey(final Object key)
            throws ClassCastException, NullPointerException {

        checkKey(key);

        return lookupValid(key, KEY, getCurrentThreadId()) != null;
    }
@Override
    public boolean containsKey(final Object key)
            throws ClassCastException, NullPointerException {

        checkKey(key);

        return lookupValid(key, KEY, getCurrentThreadId()) != null;
    }
@ Override public boolean containsKey ( final Object key ) throws ClassCastException , NullPointerException { checkKey ( key ) ; return lookupValid ( key , KEY , getCurrentThreadId ( ) ) != null ; }
Returns true if this map contains a mapping for the specified
key.

@param key key whose presence in this map is to be tested.

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

@throws ClassCastException if the key is of an inappropriate
type for this map.
@throws NullPointerException if the key is null
Returns true if this map contains a mapping for the specified key .