getMultiple returns invalid values when use a numeric key

[arima-ryunosuke]

Numeric keys (like '1') are valid keys in PSR-16.

However getMultiple returns invalid values because it uses array_merge (array_merge renumbers the numeric index of an array).
It should use array_replace here.

test code:

public function testGetMultipleWithIntegerKeys()
{
    $values = [
        '1' => uniqid('value1', true),
        '2' => uniqid('value2', true),
    ];
    $keys = array_map('strval', array_keys($values));

    $psrCache = new SimpleCacheAdapter(new ArrayCache());
    foreach ($values as $k => $v) {
        $psrCache->set((string) $k, $v);
    }

    $default = uniqid('default', true);
    $invalid_key = uniqid('key3', true);
    $keys[] = $invalid_key;
    $values[$invalid_key] = $default;

    self::assertSame($values, $psrCache->getMultiple($keys, $default));
}

results:

1) RoaveTest\DoctrineSimpleCache\SimpleCacheAdapterTest::testGetMultipleWithIntegerKeys
Failed asserting that two arrays are identical.
--- Expected
+++ Actual
@@ @@
 Array &0 (
-    1 => 'value160519bac1ea400.91716645'
-    2 => 'value260519bac1ea486.88148617'
+    0 => 'default60519bac1ea755.33267710'
+    1 => 'default60519bac1ea755.33267710'
     'key360519bac1ea776.08717164' => 'default60519bac1ea755.33267710'
+    2 => 'value160519bac1ea400.91716645'
+    3 => 'value260519bac1ea486.88148617'
 )

Fix as follows.

public function getMultiple($keys, $default = null) : array
{
    $keys = $this->filterValidateMultipleKeys($keys);
    return array_replace(array_fill_keys($keys, $default), $this->doctrineCache->fetchMultiple($keys));
}