@Nullable
    public Element getElement(@Nonnull String id) {
        if (id == null || id.trim().length() == 0) {
            throw new IllegalArgumentException("An element ID must be specified.");
        }

        return elementsById.get(id);
    }
@ Nullable public Element getElement ( @ Nonnull String id ) { if ( id == null || id . trim ( ) . length ( ) == 0 ) { throw new IllegalArgumentException ( "An element ID must be specified." ) ; } return elementsById . get ( id ) ; }
Gets the element with the specified ID.

@param id the {@link Element#getId()} of the element
@return the element in this model with the specified ID (or null if it doesn't exist)
@see Element#getId()