Issue #3327582 by jurgenhaas, tobiasb: Make the delimiter and file extension of csv source plugin overridable

src/Plugin/migrate/source/EntityImportSourceCSV.php

@@ -48,6 +48,9 @@ class EntityImportSourceCSV extends EntityImportSourceLimitIteratorBase implemen
     return $instance;
   }
 
+  protected const DELIMITER = ',';
+  protected const FILE_EXTENSION = 'csv';
+
   /**
    * {@inheritdoc}
    */
@@ -112,7 +115,7 @@ class EntityImportSourceCSV extends EntityImportSourceLimitIteratorBase implemen
       '#type' => 'managed_file',
       '#title' => $this->t('Upload File'),
       '#upload_validators' => [
-        'file_validate_extensions' => ['csv'],
+        'file_validate_extensions' => [$this::FILE_EXTENSION],
       ],
       '#required' => $this->isRequired(),
       '#multiple' => $this->hasMultiple(),
@@ -334,6 +337,7 @@ class EntityImportSourceCSV extends EntityImportSourceLimitIteratorBase implemen
     foreach ($this->getFiles() as $file) {
       $csv = Reader::createFromPath($file->getFileUri());
       $csv->setHeaderOffset(0);
+      $csv->setDelimiter($this::DELIMITER);
 
       if ($this->hasCsvEncoding()) {
         $filter = "{$this->getCsvFromEncoding()}/{$this->getCsvToEncoding()}";