Fix: Enhance JMS Header Handling for Null Values with proper Kafka Header Mapping (#154)

* This fix is to handle , When JMS header key comes as empty from MQ properties, the kafka connect pipeline is failing with NullpointerException while sinking the data to kafka . This scenario is handled in try block in the JmsToKafkaHeaderConverter class

* fix: review comments from #144 as well as add more tests

Signed-off-by: Joel Hanson <joelhanson025@gmail.com>
Co-authored-by: balajisekarraman <balajisekarraman@gmail.com>

Author: Joel-hanson

src/integration/java/com/ibm/eventstreams/connect/mqsource/MQSourceTaskIT.java

@@ -1299,4 +1299,53 @@ public void verifyLoggingErrorsWithMessageHavingDefaultRecordBuilder() throws Ex
         assertThat(processedRecords.get(0).topic()).isEqualTo("__dlq.mq.source");
         assertThat(processedRecords.get(1).topic()).isEqualTo("mytopic");
     }
+
+    @Test
+    public void verifyJmsMessageWithNullHeaders() throws Exception {
+        connectTask = getSourceTaskWithEmptyKafkaOffset();
+
+        final Map<String, String> connectorConfigProps = createDefaultConnectorProperties();
+        connectorConfigProps.put("mq.message.body.jms", "true");
+        connectorConfigProps.put("mq.record.builder", "com.ibm.eventstreams.connect.mqsource.builders.DefaultRecordBuilder");
+        connectorConfigProps.put("mq.jms.properties.copy.to.kafka.headers", "true");
+
+        connectTask.start(connectorConfigProps);
+
+        final TextMessage message = getJmsContext().createTextMessage("hello");
+        message.setStringProperty("teststring", "myvalue");
+        message.setObjectProperty("testObject", null);
+
+        putAllMessagesToQueue(DEFAULT_SOURCE_QUEUE, Arrays.asList(message));
+
+        final List<SourceRecord> kafkaMessages = connectTask.poll();
+        assertEquals(1, kafkaMessages.size());
+
+        final SourceRecord kafkaMessage = kafkaMessages.get(0);
+
+        assertThat(kafkaMessage.value()).isEqualTo("hello");
+        assertThat(kafkaMessage.headers().lastWithName("teststring").value()).isEqualTo("myvalue");
+        assertThat(kafkaMessage.headers().lastWithName("testObject").value()).isNull();
+    }
+
+    @Test
+    public void verifyJmsMessageNoHeaderCopied_WhenCopyDisabledHavingNullHeader() throws Exception {
+        connectTask = getSourceTaskWithEmptyKafkaOffset();
+
+        final Map<String, String> connectorConfigProps = createDefaultConnectorProperties();
+        connectorConfigProps.put("mq.message.body.jms", "true");
+        connectorConfigProps.put("mq.record.builder", "com.ibm.eventstreams.connect.mqsource.builders.DefaultRecordBuilder");
+        connectorConfigProps.put("mq.jms.properties.copy.to.kafka.headers", "false");
+
+        connectTask.start(connectorConfigProps);
+
+        final TextMessage message = getJmsContext().createTextMessage("hello");
+        message.setStringProperty("teststring", "myvalue");
+        message.setObjectProperty("testObject", null);
+        putAllMessagesToQueue(DEFAULT_SOURCE_QUEUE, Arrays.asList(message));
+
+        final SourceRecord kafkaMessage = connectTask.poll().get(0);
+
+        assertThat(kafkaMessage.value()).isEqualTo("hello");
+        assertThat(kafkaMessage.headers()).isEmpty();
+    }
 }

src/main/java/com/ibm/eventstreams/connect/mqsource/processor/JmsToKafkaHeaderConverter.java

@@ -24,6 +24,7 @@
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Single responsibility class to copy JMS properties to Kafka headers.
@@ -48,7 +49,10 @@ public ConnectHeaders convertJmsPropertiesToKafkaHeaders(final Message message)
 
             jmsPropertyKeys.forEach(key -> {
                 try {
-                    connectHeaders.addString(key.toString(), message.getObjectProperty(key.toString()).toString());
+                    final Object prop = message.getObjectProperty(key.toString());
+                    // this will yield `null` if prop is null, otherwise its toString()
+                    final String headerValue = Objects.toString(prop, null);
+                    connectHeaders.addString(key.toString(), headerValue);
                 } catch (final JMSException e) {
                     // Not failing the message processing if JMS properties cannot be read for some
                     // reason.

src/test/java/com/ibm/eventstreams/connect/mqsource/JmsToKafkaHeaderConverterTest.java

@@ -44,23 +44,22 @@ public class JmsToKafkaHeaderConverterTest {
     @Test
     public void convertJmsPropertiesToKafkaHeaders() throws JMSException {
 
-        final List<String> keys = Arrays.asList("facilityCountryCode", "facilityNum");
+        final List<String> keys = Arrays.asList("facilityCountryCode", "facilityNum", "nullProperty");
 
         final Enumeration<String> keyEnumeration = Collections.enumeration(keys);
 
         // Arrange
         when(message.getPropertyNames()).thenReturn(keyEnumeration);
         when(message.getObjectProperty("facilityCountryCode")).thenReturn("US");
         when(message.getObjectProperty("facilityNum")).thenReturn("12345");
+        when(message.getObjectProperty("nullProperty")).thenReturn(null);
 
         // Act
         final ConnectHeaders actualConnectHeaders = jmsToKafkaHeaderConverter
                 .convertJmsPropertiesToKafkaHeaders(message);
 
 
         //Verify
-        assertEquals("Both custom JMS properties were copied to kafka successfully.", 2, actualConnectHeaders.size());
-
-
+        assertEquals("All three custom JMS properties were copied to kafka successfully.", 3, actualConnectHeaders.size());
     }
 }