Revert "minor - fix allergy for type casting"

This reverts commit cd2adad.

src/Runner/Parallel/ParallelisationException.php

@@ -25,7 +25,7 @@ final class ParallelisationException extends \RuntimeException
 {
     public static function forUnknownIdentifier(ProcessIdentifier $identifier): self
     {
-        return new self(sprintf('Unknown process identifier: %s.', $identifier->__toString()));
+        return new self('Unknown process identifier: '.(string) $identifier);
     }
 
     /**

src/Runner/Parallel/ProcessFactory.php

@@ -80,7 +80,7 @@ public function getCommandArgs(int $serverPort, ProcessIdentifier $identifier, R
             '--port',
             (string) $serverPort,
             '--identifier',
-            escapeshellarg($identifier->__toString()),
+            escapeshellarg((string) $identifier),
         ];
 
         if ($runnerConfig->isDryRun()) {

src/Runner/Parallel/ProcessPool.php

@@ -45,21 +45,21 @@ public function __construct(ServerInterface $server, ?callable $onServerClose =
 
     public function getProcess(ProcessIdentifier $identifier): Process
     {
-        if (!isset($this->processes[$identifier->__toString()])) {
+        if (!isset($this->processes[(string) $identifier])) {
             throw ParallelisationException::forUnknownIdentifier($identifier);
         }
 
-        return $this->processes[$identifier->__toString()];
+        return $this->processes[(string) $identifier];
     }
 
     public function addProcess(ProcessIdentifier $identifier, Process $process): void
     {
-        $this->processes[$identifier->__toString()] = $process;
+        $this->processes[(string) $identifier] = $process;
     }
 
     public function endProcessIfKnown(ProcessIdentifier $identifier): void
     {
-        if (!isset($this->processes[$identifier->__toString()])) {
+        if (!isset($this->processes[(string) $identifier])) {
             return;
         }
 
@@ -77,7 +77,7 @@ private function endProcess(ProcessIdentifier $identifier): void
     {
         $this->getProcess($identifier)->quit();
 
-        unset($this->processes[$identifier->__toString()]);
+        unset($this->processes[(string) $identifier]);
 
         if (0 === \count($this->processes)) {
             $this->server->close();