Use explicit nullable type parameters (#168)

Signed-off-by: Matias Ylipelto <129368437+lianatech-matias-ylipelto@users.noreply.github.com>
Co-authored-by: Lukas Kämmerling <lukas.kaemmerling@hetzner-cloud.de>

Author: lianatech-matias-ylipelto

src/Prometheus/RegistryInterface.php

@@ -86,7 +86,7 @@ public function getOrRegisterCounter(string $namespace, string $name, string $he
      * @param string   $name e.g. duration_seconds
      * @param string   $help e.g. A histogram of the duration in seconds.
      * @param string[] $labels e.g. ['controller', 'action']
-     * @param float[]    $buckets e.g. [100, 200, 300]
+     * @param float[]|null $buckets e.g. [100, 200, 300]
      *
      * @return Histogram
      * @throws MetricsRegistrationException
@@ -96,7 +96,7 @@ public function registerHistogram(
         string $name,
         string $help,
         array $labels = [],
-        array $buckets = null
+        ?array $buckets = null
     ): Histogram;
 
     /**
@@ -113,12 +113,18 @@ public function getHistogram(string $namespace, string $name): Histogram;
      * @param string $name e.g. duration_seconds
      * @param string $help e.g. A histogram of the duration in seconds.
      * @param string[]  $labels e.g. ['controller', 'action']
-     * @param float[]  $buckets e.g. [100, 200, 300]
+     * @param float[]|null $buckets e.g. [100, 200, 300]
      *
      * @return Histogram
      * @throws MetricsRegistrationException
      */
-    public function getOrRegisterHistogram(string $namespace, string $name, string $help, array $labels = [], array $buckets = null): Histogram;
+    public function getOrRegisterHistogram(
+        string $namespace,
+        string $name,
+        string $help,
+        array $labels = [],
+        ?array $buckets = null
+    ): Histogram;
 
     /**
      * @param string   $namespace e.g. cms
@@ -137,7 +143,7 @@ public function registerSummary(
         string $help,
         array $labels = [],
         int $maxAgeSeconds = 86400,
-        array $quantiles = null
+        ?array $quantiles = null
     ): Summary;
 
     /**
@@ -160,5 +166,12 @@ public function getSummary(string $namespace, string $name): Summary;
      * @return Summary
      * @throws MetricsRegistrationException
      */
-    public function getOrRegisterSummary(string $namespace, string $name, string $help, array $labels = [], int $maxAgeSeconds = 86400, array $quantiles = null): Summary;
+    public function getOrRegisterSummary(
+        string $namespace,
+        string $name,
+        string $help,
+        array $labels = [],
+        int $maxAgeSeconds = 86400,
+        ?array $quantiles = null
+    ): Summary;
 }