[BaseCollection] Treat the null index as "no index" only while adding new element, iow. do not treat empty string as "no index" behaviour

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 Common and useful classes, methods, exceptions etc.
 
+# 1.1.1
+
+1. [BaseCollection] Treat the `null` index as "no index" only while adding new element, iow. do not treat empty
+string as "no index" behaviour.
+
 # 1.1.0
 
 1. Rename Meritoo\Common\Collection\Collection class to Meritoo\Common\Collection\BaseCollection.

VERSION

@@ -1 +1 @@
-1.1.0
+1.1.1

src/Traits/Collection/AddTrait.php

@@ -30,7 +30,7 @@ trait AddTrait
             return;
         }
 
-        if (null === $index || '' === $index) {
+        if (null === $index) {
             $this->elements[] = $element;
 
             return;

tests/Collection/BaseCollectionTest.php

@@ -438,7 +438,7 @@ class BaseCollectionTest extends BaseTestCase
             'This is test 4',
             '',
             4,
-            1,
+            '',
             new StringCollection([
                 'test1' => 'I am 1st',
                 'test2' => 'I am 2nd',