[kafka] branch 2.6 updated: KAFKA-10477: Fix JsonConverter regression to treat MISSING nodes as NULL nodes (#9306)

[rh...@apache.org]

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rhauch pushed a commit to branch 2.6
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/2.6 by this push:
     new 6c58f0d  KAFKA-10477: Fix JsonConverter regression to treat MISSING nodes as NULL nodes (#9306)
6c58f0d is described below

commit 6c58f0d4819e390f771c84a15ca52c2ecdc52b26
Author: Shaik Zakir Hussain <sh...@gmail.com>
AuthorDate: Fri Oct 2 19:51:11 2020 +0530

    KAFKA-10477: Fix JsonConverter regression to treat MISSING nodes as NULL nodes (#9306)
    
    Fixes a regression introduced in `JsonConverter` with previous upgrades from Jackson Databind 2.9.x to 2.10.x. Jackson Databind version 2.10.0 included a backward-incompatible behavioral change to use `JsonNodeType.MISSING` (and `MissingNode`, the subclass of `JsonNode` that has a type of `MISSING`) instead of `JsonNodeType.NULL` / `NullNode`. See https://github.com/FasterXML/jackson-databind/issues/2211 for details of this change.
    
    This change makes recovers the older `JsonConverter` behavior of returning null on empty input.
    
    Added two unit tests for this change. Both unit tests were independently tested with earlier released versions and passed on all versions that used Jackson 2.9.x and earlier, and failed on all versions that used 2.10.x and that did not have the fixed included in the PR. Both of the new unit tests pass with this fix to `JsonConverter`.
    
    Author: Shaik Zakir Hussain <zh...@confluent.io>
    Reviewer: Randall Hauch <rh...@gmail.com>
---
 .../apache/kafka/connect/json/JsonConverter.java   |  2 +-
 .../kafka/connect/json/JsonConverterTest.java      | 30 ++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/connect/json/src/main/java/org/apache/kafka/connect/json/JsonConverter.java b/connect/json/src/main/java/org/apache/kafka/connect/json/JsonConverter.java
index 8a2d676..1a17538 100644
--- a/connect/json/src/main/java/org/apache/kafka/connect/json/JsonConverter.java
+++ b/connect/json/src/main/java/org/apache/kafka/connect/json/JsonConverter.java
@@ -729,6 +729,7 @@ public class JsonConverter implements Converter, HeaderConverter {
         } else {
             switch (jsonValue.getNodeType()) {
                 case NULL:
+                case MISSING:
                     // Special case. With no schema
                     return null;
                 case BOOLEAN:
@@ -751,7 +752,6 @@ public class JsonConverter implements Converter, HeaderConverter {
                     break;
 
                 case BINARY:
-                case MISSING:
                 case POJO:
                 default:
                     schemaType = null;
diff --git a/connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java b/connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java
index 2e189e2..a1ac71d 100644
--- a/connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java
+++ b/connect/json/src/test/java/org/apache/kafka/connect/json/JsonConverterTest.java
@@ -195,6 +195,36 @@ public class JsonConverterTest {
         assertEquals(SchemaAndValue.NULL, converted);
     }
 
+    /**
+     * When schemas are disabled, empty data should be decoded to an empty envelope.
+     * This test verifies the case where `schemas.enable` configuration is set to false, and
+     * {@link JsonConverter} converts empty bytes to {@link SchemaAndValue#NULL}.
+     */
+    @Test
+    public void emptyBytesToConnect() {
+        // This characterizes the messages with empty data when Json schemas is disabled
+        Map<String, Boolean> props = Collections.singletonMap("schemas.enable", false);
+        converter.configure(props, true);
+        SchemaAndValue converted = converter.toConnectData(TOPIC, "".getBytes());
+        assertEquals(SchemaAndValue.NULL, converted);
+    }
+
+    /**
+     * When schemas are disabled, fields are mapped to Connect maps.
+     */
+    @Test
+    public void schemalessWithEmptyFieldValueToConnect() {
+        // This characterizes the messages with empty data when Json schemas is disabled
+        Map<String, Boolean> props = Collections.singletonMap("schemas.enable", false);
+        converter.configure(props, true);
+        String input = "{ \"a\": \"\", \"b\": null}";
+        SchemaAndValue converted = converter.toConnectData(TOPIC, input.getBytes());
+        Map<String, String> expected = new HashMap<>();
+        expected.put("a", "");
+        expected.put("b", null);
+        assertEquals(new SchemaAndValue(null, expected), converted);
+    }
+
     @Test
     public void nullSchemaPrimitiveToConnect() {
         SchemaAndValue converted = converter.toConnectData(TOPIC, "{ \"schema\": null, \"payload\": null }".getBytes());