I just found code like this in a (quite expensive) Java framework i was evaluating (Note: I edited the API Documentation and the name of the method):

     * Used to set some value and change some behaviour based on this
     * value.
     * API users should not call this method with {@code false}.
     * Instead you should invoke 
     * {@link #anotherMethodThatDoesTheOpposite()}.
     * @param b   {@code true} to do something (false does nothing)
    public void setSomeValue(boolean b) {
        /* here is some code that does something if b is true */

Nice, isn’t it? A method with a boolean parameter which must be true.