fix(Sharing): Ensure share object has null expiration when required

If the incoming `expireDate` is an empty string, we want to ensure the share object itself
gets valid date for for empty string which is `null` before attempting to save.

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

Author: nfebe

lib/private/Share20/Manager.php

@@ -451,6 +451,8 @@ protected function validateExpirationDateInternal(IShare $share) {
 					throw new GenericShareException($message, $message, 404);
 				}
 			}
+		} else {
+			$expirationDate = null;
 		}
 
 		$accepted = true;
@@ -532,6 +534,8 @@ protected function validateExpirationDateLink(IShare $share) {
 					throw new GenericShareException($message, $message, 404);
 				}
 			}
+		} else {
+			$expirationDate = null;
 		}
 
 		$accepted = true;
@@ -1020,15 +1024,15 @@ public function updateShare(IShare $share) {
 
 			if ($share->getExpirationDate() != $originalShare->getExpirationDate()) {
 				//Verify the expiration date
-				$this->validateExpirationDateInternal($share);
+				$share = $this->validateExpirationDateInternal($share);
 				$expirationDateUpdated = true;
 			}
 		} elseif ($share->getShareType() === IShare::TYPE_GROUP) {
 			$this->groupCreateChecks($share);
 
 			if ($share->getExpirationDate() != $originalShare->getExpirationDate()) {
 				//Verify the expiration date
-				$this->validateExpirationDateInternal($share);
+				$share = $this->validateExpirationDateInternal($share);
 				$expirationDateUpdated = true;
 			}
 		} elseif ($share->getShareType() === IShare::TYPE_LINK
@@ -1064,13 +1068,13 @@ public function updateShare(IShare $share) {
 
 			if ($share->getExpirationDate() != $originalShare->getExpirationDate()) {
 				// Verify the expiration date
-				$this->validateExpirationDateLink($share);
+				$share = $this->validateExpirationDateLink($share);
 				$expirationDateUpdated = true;
 			}
 		} elseif ($share->getShareType() === IShare::TYPE_REMOTE || $share->getShareType() === IShare::TYPE_REMOTE_GROUP) {
 			if ($share->getExpirationDate() != $originalShare->getExpirationDate()) {
 				//Verify the expiration date
-				$this->validateExpirationDateInternal($share);
+				$share = $this->validateExpirationDateInternal($share);
 				$expirationDateUpdated = true;
 			}
 		}