Generate EXTENDED_JSON label in pipelines

If `JSON` is present in the actual string content, using `<<< JSON` as
the multiline string label is considered unsafe and rector will scream
about it (`SensitiveHereNowDocRector`)

Seeing as `EXTENDED_JSON` is not and probably will never be present in
the strings, use that for the heredoc/nowdoc to circumvent
`SensitiveHereNowDocRector`

Author: paulinevos

generator/src/OperatorTestGenerator.php

@@ -127,7 +127,7 @@ public function createClass(GeneratorDefinition $definition, OperatorDefinition
 
                 $json = Document::fromPHP($filterAndUpdate)->toCanonicalExtendedJSON();
                 $json = json_encode(json_decode($json), JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
-                $case = $dataEnum->addCase($caseName, new Literal('<<<\'JSON\'' . "\n" . $json . "\n" . 'JSON'));
+                $case = $dataEnum->addCase($caseName, $this->jsonLiteral($json));
                 $case->setComment($test->name);
                 if ($test->link) {
                     $case->addComment('');
@@ -159,7 +159,7 @@ public function createClass(GeneratorDefinition $definition, OperatorDefinition
                 $json = Document::fromPHP(['pipeline' => $pipeline])->toCanonicalExtendedJSON();
                 // Unwrap the pipeline array and reformat for prettier JSON
                 $json = json_encode(json_decode($json)->pipeline, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
-                $case = $dataEnum->addCase($caseName, new Literal('<<<\'JSON\'' . "\n" . $json . "\n" . 'JSON'));
+                $case = $dataEnum->addCase($caseName, $this->jsonLiteral($json));
                 $case->setComment($test->name);
                 if ($test->link) {
                     $case->addComment('');
@@ -191,6 +191,11 @@ public function createClass(GeneratorDefinition $definition, OperatorDefinition
         return $namespace;
     }
 
+    private function jsonLiteral(string $json): Literal
+    {
+        return new Literal('<<<\'EXTENDED_JSON\'' . "\n" . $json . "\n" . 'EXTENDED_JSON');
+    }
+
     private function convertYamlTaggedValues(mixed $object): mixed
     {
         if ($object instanceof TaggedValue) {