[BUGFIX] Fix SubscriberList to Subscriber relationship definition by …

.github/CONTRIBUTING.md

@@ -105,6 +105,11 @@ After that has been done, you can run the integration tests:
 vendor/bin/phpunit tests/Integration/
 ```
 
+When changing database relations and entities please ensure the mapping is valid by running:
+
+```bash
+bin/console doctrine:schema:validate
+```
 
 ## Coding Style
 

.travis.yml

@@ -56,6 +56,11 @@ script:
   echo "Validating the composer.json";
   composer validate --no-check-all --no-check-lock --strict;
 
+- >
+  echo;
+  echo "Doctrine database schema validation";
+  bin/console doctrine:schema:validate;
+
 - >
   echo;
   echo "Linting all PHP files";

src/Domain/Model/Subscription/Subscriber.php

@@ -118,7 +118,7 @@ class Subscriber implements DomainModel, Identity, CreationDate, ModificationDat
 
     /**
      * @var Collection
-     * @Mapping\ManyToMany(targetEntity="PhpList\Core\Domain\Model\Messaging\SubscriberList", inversedBy="subscribers")
+     * @Mapping\ManyToMany(targetEntity="PhpList\Core\Domain\Model\Messaging\SubscriberList", mappedBy="subscribers")
      * @Mapping\JoinTable(name="phplist_listuser",
      *     joinColumns={@Mapping\JoinColumn(name="userid")},
      *     inverseJoinColumns={@Mapping\JoinColumn(name="listid")}