make projectName nullable, because it is not enforced (although probably filled everywhere)

Author: odinuv

src/JobFactory/PlainJob.php

@@ -158,9 +158,9 @@ public function getProjectId(): string
         return $this->data['projectId'];
     }
 
-    public function getProjectName(): string
+    public function getProjectName(): ?string
     {
-        return $this->data['projectName'] ?? '';
+        return $this->data['projectName'] ?? null;
     }
 
     public function getResult(): array

src/JobFactory/PlainJobInterface.php

@@ -86,7 +86,7 @@ public function getConfigData(): array;
     public function getConfigId(): ?string;
     public function getMode(): string;
     public function getProjectId(): string;
-    public function getProjectName(): string;
+    public function getProjectName(): ?string;
     public function getResult(): array;
     public function getConfigRowIds(): array;
     public function getStatus(): string;