Fixing SamplingServiceTests.testMaybeSampleMaxSize()

server/src/test/java/org/elasticsearch/ingest/SamplingServiceTests.java

@@ -250,7 +250,7 @@ public void testMaybeSampleMaxSize() {
             );
         final ProjectId projectId = projectBuilder.getId();
         ProjectMetadata projectMetadata = projectBuilder.build();
-        final IndexRequest indexRequest = new IndexRequest(indexName).id("_id").source(randomByteArrayOfLength(150), XContentType.JSON);
+        final IndexRequest indexRequest = new IndexRequest(indexName).id("_id").source(randomAsciiByteArrayOfLength(150), XContentType.JSON);
         for (int i = 0; i < maxSamples; i++) {
             samplingService.maybeSample(projectMetadata, indexRequest);
         }
@@ -353,4 +353,15 @@ private SamplingService getTestSamplingService() {
         final ProjectResolver projectResolver = TestProjectResolvers.singleProject(projectId);
         return new SamplingService(scriptService, clusterService, projectResolver, System::currentTimeMillis);
     }
+
+    /*
+     * Returns an array containing random bytes that correspond to valid ascii characters
+     */
+    private static byte[] randomAsciiByteArrayOfLength(int size) {
+        byte[] bytes = new byte[size];
+        for (int i = 0; i < size; i++) {
+            bytes[i] = (byte) randomIntBetween(0, 127);
+        }
+        return bytes;
+    }
 }