Implement review suggestions

Author: luigidellaquila

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/generative/EsqlQueryGenerator.java

@@ -527,6 +527,8 @@ private static String constantExpression() {
     }
 
     private static String randomIdentifier() {
+        // Let's create identifiers that are long enough to avoid collisions with reserved keywords.
+        // There could be a smarter way (introspection on the lexer class?), but probably it's not worth the effort
         return randomAlphaOfLength(randomIntBetween(8, 12));
     }
 

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/CsvTestsDataLoader.java

@@ -315,7 +315,7 @@ private static boolean isLookupDataset(TestDataset dataset) throws IOException {
         return (mode != null && mode.equalsIgnoreCase("lookup"));
     }
 
-    public static boolean isSourceMappingDataset(TestDataset dataset) throws IOException {
+    private static boolean isSourceMappingDataset(TestDataset dataset) throws IOException {
         if (dataset.mappingFileName() == null) {
             return true;
         }