public URI getRequiredURI(String key) {
        Optional<String> property = getString(key);
        if (property.isPresent()) {
            return URIUtils.create(property.get());
        } else {
            throw new IllegalStateException(String.format("required key [%s] not found", key));
        }
    }
public URI getRequiredURI ( String key ) { Optional < String > property = getString ( key ) ; if ( property . isPresent ( ) ) { return URIUtils . create ( property . get ( ) ) ; } else { throw new IllegalStateException ( String . format ( "required key [%s] not found" , key ) ) ; } }
Return the URI property value associated with the given key (never {@code null}).

@return The URI property
@throws IllegalStateException if the key cannot be resolved