Address Nik's feedback

Author: mayya-sharipova

rest-api-spec/src/main/resources/rest-api-spec/test/search/350_binary_field.yml

@@ -20,13 +20,11 @@
             Content-Type: application/json
         index:
             index: test
+            refresh: true
             id: 1
             body:
                 binary: U29tZSBiaW5hcnkgYmxvYg==
 
-    - do:
-        indices.refresh: {}
-
     - do:
         search:
             index: test

server/src/test/java/org/elasticsearch/index/mapper/BinaryFieldMapperTests.java

@@ -19,7 +19,9 @@
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
+import java.util.Base64;
 
 import static org.hamcrest.Matchers.instanceOf;
 
@@ -121,9 +123,12 @@ public void testStoredValue() throws IOException {
 
     @Override
     protected Object generateRandomInputValue(MappedFieldType ft) {
-        assumeFalse("We can't parse the binary doc values we send", true);
-        // AwaitsFix https://github.com/elastic/elasticsearch/issues/70244
-        return null;
+        if (rarely()) {
+            return null;
+        } else {
+            byte[] value = randomAlphaOfLengthBetween(1, 30).getBytes(StandardCharsets.UTF_8);
+            return Base64.getEncoder().encodeToString(value);
+        }
     }
 
     @Override