fix assertion deprecation (#2068)

src/Entity/ColorTrait.php

@@ -28,7 +28,7 @@ trait ColorTrait
      * @Exporter\Expose(label="label.color")
      *
      * @ORM\Column(name="color", type="string", length=7, nullable=true)
-     * @Assert\Length(min=4, max=7)
+     * @Assert\Length(min=4, max=7, allowEmptyString=true)
      */
     private $color = null;
 

src/Entity/Invoice.php

@@ -138,7 +138,7 @@ class Invoice
      *
      * @ORM\Column(name="invoice_filename", type="string", length=150, nullable=false)
      * @Assert\NotNull()
-     * @Assert\Length(min=1, max=150)
+     * @Assert\Length(min=1, max=150, allowEmptyString=false)
      */
     private $invoiceFilename;
 

src/Entity/Role.php

@@ -38,7 +38,7 @@ class Role
      * @ORM\Column(name="name", type="string", length=50, nullable=false)
      * @Assert\NotNull()
      * @Assert\NotBlank()
-     * @Assert\Length(allowEmptyString=false, min=5, max=50)
+     * @Assert\Length(min=5, max=50, allowEmptyString=false)
      */
     private $name;