add annotations for thrown exceptions

src/Generator/TimeGeneratorInterface.php

@@ -30,6 +30,10 @@ interface TimeGeneratorInterface
      *     could arise when the clock is set backwards in time or if the node ID
      *     changes.
      * @return string A binary string
+     * @throws \Ramsey\Uuid\Exception\UnsatisfiedDependencyException if called on a 32-bit system and
+     *     `Moontoast\Math\BigNumber` is not present
+     * @throws \InvalidArgumentException
+     * @throws \Exception if it was not possible to gather sufficient entropy
      */
     public function generate($node = null, $clockSeq = null);
 }