add more purity and immutable markers

src/Async/EventStoreConnection.php

@@ -43,6 +43,7 @@ interface EventStoreConnection
 {
     public function connectionName(): string;
 
+    /** @return Promise<void> */
     public function connectAsync(): Promise;
 
     public function close(): void;

src/EndPoint.php

@@ -13,6 +13,7 @@
 
 namespace Prooph\EventStore;
 
+/** @psalm-immutable */
 class EndPoint
 {
     private string $host;
@@ -24,21 +25,25 @@ public function __construct(string $host, int $port)
         $this->port = $port;
     }
 
+    /** @psalm-pure */
     public function host(): string
     {
         return $this->host;
     }
 
+    /** @psalm-pure */
     public function port(): int
     {
         return $this->port;
     }
 
+    /** @psalm-pure */
     public function equals(EndPoint $endPoint): bool
     {
         return $this->host === $endPoint->host && $this->port === $endPoint->port;
     }
 
+    /** @psalm-pure */
     public function __toString(): string
     {
         return $this->host . ':' . $this->port;

src/UserCredentials.php

@@ -15,6 +15,7 @@
 
 use Prooph\EventStore\Exception\InvalidArgumentException;
 
+/** @psalm-immutable */
 class UserCredentials
 {
     private string $username;
@@ -34,11 +35,13 @@ public function __construct(string $username, string $password)
         $this->password = $password;
     }
 
+    /** @psalm-pure */
     public function username(): string
     {
         return $this->username;
     }
 
+    /** @psalm-pure */
     public function password(): string
     {
         return $this->password;