Issue #3376601: Use validation functions from the libphonenumber library

src/Plugin/Validation/Constraint/PhoneNumberConstraint.php

@@ -40,6 +40,12 @@ class PhoneNumberConstraint extends Constraint {
    */
   public $allowedCountry = 'The country @value provided for @field_name is not an allowed country.';
 
+  /**
+   * The invalid number message.
+   *
+   * @var string
+   */
+  public $invalidNumber = 'The @field_name @value is not a valid phone number.';
   /**
    * {@inheritdoc}
    */