Issue #3427431 by rob_pr: SimpleFieldMapper produces extra null value

src/Plugin/ExternalEntities/FieldMapper/SimpleFieldMapper.php

@@ -277,7 +277,7 @@ class SimpleFieldMapper extends ConfigurableExpressionFieldMapperBase {
       $raw_values = [$raw_values];
     }
 
-    foreach (range(0, count($raw_values)) as $delta_index) {
+    for ($delta_index = 0; $delta_index < count($raw_values); ++$delta_index) {
       $new_seen_mapping_keys = array_merge($seen_mapping_keys, [$delta_index]);
 
       $values = $this->recursiveMapFieldFromRawData(