interface TextMapPropagatorInterface

interface TextMapPropagatorInterface {
    
    /**
     * Returns list of fields that will be used by this propagator.
     *
     * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/context/api-propagators.md#fields
     *
     * @return list<string>
     */
    public function fields() : array;
    
    /**
     * Injects specific values from the provided {@see ContextInterface} into the provided carrier
     * via an {@see PropagationSetterInterface}.
     *
     * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/context/api-propagators.md#textmap-inject
     */
    public function inject(mixed &$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null) : void;
    
    /**
     * Extracts specific values from the provided carrier into the provided {@see ContextInterface}
     * via an {@see PropagationGetterInterface}.
     *
     * @see https://github.com/open-telemetry/opentelemetry-specification/blob/v1.6.1/specification/context/api-propagators.md#textmap-extract
     */
    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null) : ContextInterface;

}