Add duplicate check, examples for kafka Properties

Added checks for dealing with duplication of specification of properties
explicitly and in kafkaPropertes
Added examples for kafkaProperties
Added documentation for kafkaProperties

Issue-ID: POLICY-1818
Change-Id: Icbe01d6f1d25d4570dcc85cc3db28588743b9c41
Signed-off-by: liamfallon <liam.fallon@est.tech>

1 files changed, 55 insertions, 24 deletions

diff --git a/plugins/plugins-event/plugins-event-carrier/plugins-event-carrier-kafka/src/main/java/org/onap/policy/apex/plugins/event/carrier/kafka/KafkaCarrierTechnologyParameters.java b/plugins/plugins-event/plugins-event-carrier/plugins-event-carrier-kafka/src/main/java/org/onap/policy/apex/plugins/event/carrier/kafka/KafkaCarrierTechnologyParameters.java
index 927d79ee1..9d9acf625 100644
--- a/plugins/plugins-event/plugins-event-carrier/plugins-event-carrier-kafka/src/main/java/org/onap/policy/apex/plugins/event/carrier/kafka/KafkaCarrierTechnologyParameters.java
+++ b/plugins/plugins-event/plugins-event-carrier/plugins-event-carrier-kafka/src/main/java/org/onap/policy/apex/plugins/event/carrier/kafka/KafkaCarrierTechnologyParameters.java
@@ -154,26 +154,28 @@ public class KafkaCarrierTechnologyParameters extends CarrierTechnologyParameter
      * @return the kafka producer properties
      */
     public Properties getKafkaProducerProperties() {
-        final Properties returnKafkaProperties = new Properties();
+        final Properties retKafkaProps = new Properties();
 
         // Add properties from the Kafka property array
         if (kafkaProperties != null) {
             for (int i = 0; i < kafkaProperties.length; i++) {
-                returnKafkaProperties.put(kafkaProperties[i][0], kafkaProperties[i][1]);
+                retKafkaProps.setProperty(kafkaProperties[i][0], kafkaProperties[i][1]);
             }
         }
 
-        returnKafkaProperties.put(PROPERTY_BOOTSTRAP_SERVERS, bootstrapServers);
-        returnKafkaProperties.put(PROPERTY_ACKS, acks);
-        returnKafkaProperties.put(PROPERTY_RETRIES, retries);
-        returnKafkaProperties.put(PROPERTY_BATCH_SIZE, batchSize);
-        returnKafkaProperties.put(PROPERTY_LINGER_TIME, lingerTime);
-        returnKafkaProperties.put(PROPERTY_BUFFER_MEMORY, bufferMemory);
-        returnKafkaProperties.put(PROPERTY_KEY_SERIALIZER, keySerializer);
-        returnKafkaProperties.put(PROPERTY_VALUE_SERIALIZER, valueSerializer);
-        returnKafkaProperties.put(PROPERTY_PARTITIONER_CLASS, partitionerClass);
-
-        return returnKafkaProperties;
+        // @formatter:off
+        putExplicitProperty(retKafkaProps, PROPERTY_BOOTSTRAP_SERVERS, bootstrapServers, DEFAULT_BOOT_SERVERS);
+        putExplicitProperty(retKafkaProps, PROPERTY_ACKS,              acks,             DEFAULT_ACKS);
+        putExplicitProperty(retKafkaProps, PROPERTY_RETRIES,           retries,          DEFAULT_RETRIES);
+        putExplicitProperty(retKafkaProps, PROPERTY_BATCH_SIZE,        batchSize,        DEFAULT_BATCH_SIZE);
+        putExplicitProperty(retKafkaProps, PROPERTY_LINGER_TIME,       lingerTime,       DEFAULT_LINGER_TIME);
+        putExplicitProperty(retKafkaProps, PROPERTY_BUFFER_MEMORY,     bufferMemory,     DEFAULT_BUFFER_MEMORY);
+        putExplicitProperty(retKafkaProps, PROPERTY_KEY_SERIALIZER,    keySerializer,    DEFAULT_STRING_SERZER);
+        putExplicitProperty(retKafkaProps, PROPERTY_VALUE_SERIALIZER,  valueSerializer,  DEFAULT_STRING_SERZER);
+        putExplicitProperty(retKafkaProps, PROPERTY_PARTITIONER_CLASS, partitionerClass, DEFAULT_PARTITIONR_CLASS);
+        // @formatter:on
+
+        return retKafkaProps;
     }
 
     /**
@@ -182,24 +184,26 @@ public class KafkaCarrierTechnologyParameters extends CarrierTechnologyParameter
      * @return the kafka consumer properties
      */
     public Properties getKafkaConsumerProperties() {
-        final Properties returnKafkaProperties = new Properties();
+        final Properties retKafkaProps = new Properties();
 
         // Add properties from the Kafka property array
         if (kafkaProperties != null) {
             for (int i = 0; i < kafkaProperties.length; i++) {
-                returnKafkaProperties.put(kafkaProperties[i][0], kafkaProperties[i][1]);
+                retKafkaProps.setProperty(kafkaProperties[i][0], kafkaProperties[i][1]);
             }
         }
 
-        returnKafkaProperties.put(PROPERTY_BOOTSTRAP_SERVERS, bootstrapServers);
-        returnKafkaProperties.put(PROPERTY_GROUP_ID, groupId);
-        returnKafkaProperties.put(PROPERTY_ENABLE_AUTO_COMMIT, enableAutoCommit);
-        returnKafkaProperties.put(PROPERTY_AUTO_COMMIT_TIME, autoCommitTime);
-        returnKafkaProperties.put(PROPERTY_SESSION_TIMEOUT, sessionTimeout);
-        returnKafkaProperties.put(PROPERTY_KEY_DESERIALIZER, keyDeserializer);
-        returnKafkaProperties.put(PROPERTY_VALUE_DESERIALIZER, valueDeserializer);
-
-        return returnKafkaProperties;
+        // @formatter:off
+        putExplicitProperty(retKafkaProps, PROPERTY_BOOTSTRAP_SERVERS,  bootstrapServers, DEFAULT_BOOT_SERVERS);
+        putExplicitProperty(retKafkaProps, PROPERTY_GROUP_ID,           groupId,          DEFAULT_GROUP_ID);
+        putExplicitProperty(retKafkaProps, PROPERTY_ENABLE_AUTO_COMMIT, enableAutoCommit, DEFAULT_ENABLE_AUTOCMIT);
+        putExplicitProperty(retKafkaProps, PROPERTY_AUTO_COMMIT_TIME,   autoCommitTime,   DEFAULT_AUTO_COMMIT_TIME);
+        putExplicitProperty(retKafkaProps, PROPERTY_SESSION_TIMEOUT,    sessionTimeout,   DEFAULT_SESSION_TIMEOUT);
+        putExplicitProperty(retKafkaProps, PROPERTY_KEY_DESERIALIZER,   keyDeserializer,  DEFAULT_STRING_DESZER);
+        putExplicitProperty(retKafkaProps, PROPERTY_VALUE_DESERIALIZER, valueDeserializer, DEFAULT_STRING_DESZER);
+        // @formatter:on
+
+        return retKafkaProps;
     }
 
     /**
@@ -285,4 +289,31 @@ public class KafkaCarrierTechnologyParameters extends CarrierTechnologyParameter
             }
         }
     }
+
+    /**
+     * Put a property into the properties if it is not already defined and is not the default value.
+     *
+     * @param returnKafkaProperties the properties to set the value in
+     * @param property the property to put
+     * @param value the value of the property to put
+     * @param defaultValue the default value of the property to put
+     */
+    private void putExplicitProperty(final Properties returnKafkaProperties, final String property,
+            final Object value, final Object defaultValue) {
+
+        // Check if the property is already in the properties
+        if (!returnKafkaProperties.containsKey(property)) {
+            // Not found, so add it
+            returnKafkaProperties.setProperty(property, value.toString());
+        }
+        else {
+            // Found, only overwrite if the property does not have the default value
+            if (value == null) {
+                returnKafkaProperties.setProperty(property, defaultValue.toString());
+            }
+            else if (!value.toString().contentEquals(defaultValue.toString())) {
+                returnKafkaProperties.setProperty(property, value.toString());
+            }
+        }
+    }
 }